PART I: INORGANIC CHEMISTRY UNIT I: Introduction to Chemistry SCIENCE is a systematized knowledge based on facts and principles taken or derived from hypothesis and experimentation which help man understand the world around him. Fields of Science Social Science deals with institutions or organizations functioning in a society; and of human behaviors and relationships Politics Economics History Natural Science deals with the study of nature (measurable phenomena) Biological sciences – living things o Zoology o Botany o Microbiology Physical sciences – nonliving things o Physics o Chemistry o Geology o Astronomy o Meteorology Applied Science deals with the application of the theoretical sciences (social and natural sciences) Medicine Engineering Architecture CHEMISTRY describes matter, its properties, the changes it undergoes, and the energy that accompany those processes. CHEMICAL TECHNOLOGY deals with the application of the principles of chemistry for practical use. 1 History of Chemistry The earliest practical knowledge of chemistry was concerned with metallurgy, pottery and dyes. These crafts were developed with considerable skill, but with no understanding of the principles involved, as early as 3500 B.C in Egypt and Mesopotamia. Basic ideas of element and compound were first formulated by the Greek philosophers in 500 BC – 300 BC. Generally there were 4 elements (fire, air, water, earth) combined in varying proportions to form all things. Aristotle’s definition of a simple body as ‘one into which other bodies can be decomposed and which itself is not capable of being divided’ is close to the modern definition of element. Ancient Egyptian industrial arts and Greek philosophical speculations were fused into a new science at the beginning of the Christian era in Alexandria. This became the beginning of alchemy (medieval form of chemistry) which used occultism and magic. Interest of the period: transmutation of base metals into gold imitation of precious gems search for the elixir of life ( thought to grant immortality) Muslim conquest in 7th century A.D. diffused the remains of Hellenistic civilization to the Arab world. The first chemical treatises to become well-known in Europe were Latin translations of Arabic works; hence, it is often erroneously supposed that chemistry originated among the Arabs. Alchemy developed extensively during the middle Ages, cultivated largely by itinerant scholars who wandered over Europe looking for patrons. Evolution of Modern Chemistry Scientist Robert Boyle (1627-1691) Contribution He performed experiments under reduced pressure using an air pump and discovered that volume and pressure are inversely related in gases. Robert Hooke (1635-1703) He gave the first rational explanation of combustion as combination with air. John Mayow (1641-1679) He postulated that the air needed in lighting a candle is the same air needed by animals to survive. Johann Joachim Becher (1635-1682) George Ernst Stahl (1660-1734) They introduced the phlogiston theory of combustion which held that the substance phlogiston is contained in all combustible bodies and escapes when the bodies burn. 2 Jan Baptist van Helmont (1589-1644) He was the first to describe carbon dioxide as “gas sylvestre” given off by burning charcoal and this gas was the same as that produced by fermenting grapes which sometimes renders the air of caves unbreathable. Joseph Black (1728-1799) He was the first person to isolate carbon dioxide in a perfectly pure state using carbonates. Joseph Priestly (1733-1804) He discovered the “dephogisticated air” by heating a nonmetallic red power (mercuric oxide) in a jar inverted in a bowl of mercury. Antoine Lavoisier named the dephogisticated air as oxygen. Henry Cavendish (1731-1810) He isolated a very light, highly flammable gas by reacting metals with acids; when this gas is burned, pure water was produced. Antoine Lavoisier named the gas hydrogen. Branches of Chemistry Branch Inorganic Chemistry Description It is the study of almost all the elements and their compounds except carbon and its compounds. Some simple carbon compounds are traditionally classified as inorganic since they are derived from mineral sources. Organic Chemistry It is the study of carbon and its compounds, considering at least carboncarbon or carbon-hydrogen chain except urea. Analytic Chemistry It is the identification of the composition, both quantitative (how much is present) and qualitative (what is present) of a substance. Biochemistry It is the study of the composition and processes that occur in living organisms. Physical Chemistry It is the study of theories, principles and laws that govern the structure and changes in matter. Environmental Chemistry It is the study of the composition, nature and concentration of pollutants and other substances affecting the environment. Nuclear Chemistry It is the study of atomic nucleus, its reactions and the products of such reactions. Industrial Chemistry It is the study of the physical and chemical processes applied in the manufacture of substances 3 The Scientific Method is a systematic approach in problem solving. stating the problem clear statement manageable scope gathering information on the problem observation or research formulation of hypothesis proposed solution to a problem tentative answer-models performing the experiment variable – factor that is being tested (experimental set-up) recording and analyzing data data – recorded observations and measurements data table – is a chart that organizes information in rows and columns graph – is data shown in the form of a picture stating a conclusion conclusion – final answer to the problem theory – logical explanation of events that occur in nature supported by results obtained from repeated experiments where further experiments, new phenomena could be discovered law – statement that summarizes the results of observations and experiments; a precise statement which describes a mode of behavior or pattern of action about a large number of related facts Scientific Attitudes 1. curiosity 2. determination 3. open-mindedness 4. acceptance of failure 5. objectivity 6. humility 7. skepticism 8. patience Importance of Chemistry 1. In the field of _____, it enables scientists to investigate and discover the properties of raw materials in the purpose of processing them into new products as well as improve existing ones. 2. In agriculture, chemistry is used in soil analysis and in the manufacture of fertilizers and insecticides increasing production. 3. In medicine, chemistry is employed to discover new minerals and vitamins to improve health and to understand human ailments and to invent drugs to cure diseases. 4. In industry, chemistry makes possible the manufacture of new and better economic goods, the invention of better appliances and the development of new technologies for processing goods for our consumption Concerns of Chemistry 1. worldwide food shortage 2. development of pharmaceutical chemicals 3. dwindling natural resources and pollution 4 FUNDAMENTALS OF MEASUREMENT Measurement is a process of comparing a thing with a standard. It is very important in giving more precise quantitative and qualitative description of an object. Methods of measurements Direct measurement Measuring things with the use of an instrument Indirect measurement Measuring things using mathematical calculation Kinds of measurable quantities Fundamental quantities Measured by direct method Derived quantities Formulated based on the fundamental quantities BASE UNITS Fundamental units of the international system Measurement Length Mass Time Thermodynamic temperature Electric current Amount of substance Luminary intensity Unit Symbol Meter Kilogram Second Kelvin m kg s K Ampere Mole Candela A mol cd DERIVED UNITS AREA VOLUME DENSITY m x m = m2 cm x cm x cm = cm3 ρ = kg/cm3 = kg/cm3 Multiply two lengths Multiply 3 lengths together Mass per unit volume (D= M/V) 5 System of measurement Metric system/SI/international system of units Variations: MKS – meter-kilogram-second CGS – centimeter-gram-second English or British system FPS system - foot-pound-second The following are prefixes used to express bigger and smaller units: Symbol Prefix Exponential yotta Y 1024 zetta Z 1021 exa E 1018 peta P 1015 tera T 1012 giga G 109 mega M 106 kilo k 103 hecto h 102 deca da 101 deci d 10¯1 centi c 10¯2 milli m 10¯3 micro µ 10¯6 nano n 10¯9 pico p 10¯12 femto f 10¯15 atto a 10¯18 zepto z 10¯21 yocto y 10¯24 6 SIGNIFICANT FIGURES They comprise all digits that are known with certainty plus the first digit that is uncertain. The position of the decimal point is relevant. Rules in counting significant figures Rule Measurement Expression Significant Figures 1. All nonzero digits are significant. 14567.3 34.128 3.986 6 5 4 2. All zeros between two nonzero digits are significant. 34.0045 1.00006017 20037089 6 9 8 3. Zeros to the right of a nonzero digit, but to the left of an understood decimal point, are not significant unless specifically indicated as significant by a bar placed above the rightmost, such zero becomes significant. 108,000000 108,0000 _ 108,000000 3 4 9 4. All zeros to the right of a decimal point but to the left of a nonzero digit are not significant.* 0.000509 0.02876 0.0000036 3 4 2 5. All zeros to the right of a decimal point and to the right of a nonzero digit are significant. 0.4087 0.030670890 700.00000000 4 8 11 *The single zero conventionally placed to the left of a decimal point in such an expression is never significant. It is just used to locate the decimal point. OPERATIONS WITH SIGNIFICANT FIGURES Addition and Subtraction The answer must contain the same number of decimal places as the term with the least number of significant figures. Examples: a. 20.63 + 6.6 cm + 3. 786 cm = 31.016 cm b. 387.876 L – 197.23L = 190.646 L ans. 31.0 cm ans. 190.65 L 7 Multiplication and Division The answer must contain the same number of significant figures as the term with the least number of significant figures. Examples: a. 9.25 m x 0.52 m x 11. 35m = 54.5935 m3 b. 69.48 m by 3.62 s = 19.19337017 m/s ans. 55 m3 ans. 19.2 m/s SCIENTIFIC NOTATION Method of writing or expressing very large or very small numbers into its exponential form. Form: M x 10n Where: M - number lower than one and not greater than ten N - number of times the decimal point is moved. It can be a positive or negative integer. Rules: 1. Determine M by moving the decimal point in the original number to the left or right so that the only one nonzero digit is to the left of it. 2. Determine n by counting the number of places the decimal point has been moved. If moved to the left, n is positive. If moved to the right, n is negative. Examples: Diameter of the earth Diameter of a hydrogen atom Speed of light Positional form Exponential form = 1 300 000 000 ans. 1.3 x 109 cm = 0.000 000 01 cm ans. 1 x 10- 8 cm = 30 000 000 000 cm/s ans. 3 x 1010cm/s ROUNDING OFF NUMBERS 1. If the figure to be dropped is five, or greater than five, increase by one the value of the last figure to be retained. Examples: a) 78.567 rounded off to the nearest hundredths place is 78.57 b) 123.345 rounded off to the nearest hundredths place is 123.35 c) 457.9679 rounded off to the nearest thousandths place is 457.968 2. If the figure to be dropped is less than five, the last figure to be retained should not be changed. Examples: a) 5.052 rounded off to the nearest hundredths place is 5.05. b) 136.324 rounded off to the nearest ones place is 136 c) 98230.478 rounded off to the nearest tens place is 98230 8 CONVERSION OF UNITS A unit conversion factor is used to covert a quantity in one system of units to corresponding quantity in another system of units. METRIC to ENGLISH 1cm = 0.3937 in = 0.03281 ft 1m = 39.37 in 3.281 ft = 1.094 yd ENGLISH to METRIC 1 in = 2.54 cm = 0.0254 m 1ft = 30.5 cm = 0.305 m 1 km = 3281 ft = 0.6214 mi 1 yd = 91.4 cm = 0.914 m 1cm3 = 0.0610 in3 0.0000 353 ft3 1 mi = 1609 m =1.609 km 1L = 1.06 qt = 0.265 gal = 0.0353 ft3 1 qt = 946 ml = 0.946 L 1g = 0.0353 oz = 0.00220 lb 1 oz = 28350 mg = 28.35 g 1kg = 2.20 lb = 0.00110 tn 1lb = 453.6 g = 0.4536 kg 1 metric tn (103kg)= 2200 lb = 1.10 tn 1 tn =907 kg = 0.907 metric tn UNCERTAINTIES IN MEASUREMENT The experimental process is an essential part of chemistry, and reliable measurement information is an essential part of the experimental process. Unfortunately, the measurement of any physical quantity is subject to some uncertainty. Consequently, the complete expression of a measured quantity must include the number value, the measurement unit used, and some indications of how reliable the number is. Contributions to the uncertainty in measurements of physical quantities accrue from limitations in accuracy and limitations in precision inherent in all measurement process. PRECISION AND ACCURACY Dependent on measuring device used and the skill of the person measuring. PRECISION refers to the degree to which successive measurements agree with each other. ACCURACY is how close or the nearness of a measurement to its accepted value. PERCENTAGE ERROR % = Difference between the two values / true value x 100 % 9 SAMPLE PROBLEMS: DENSITY ρ = m/v 1. 2. 3. 4. 5. 6. 7. 8. 9. Calculate the density of a material that has a mass of 52.457 g and a volume of 13.5 cm 3. (3.89 g/cm3) A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock is 22.7 cm3, and the mass in 39.943 g. What is the density of the rock? (1.76 g/cm3) If 30.943 g of a liquid occupy a space of 35.0 ml, what is the density of the liquid in g/cm 3? (0.884 g/cm3) The density of silver is 10.49 g/cm3. If a sample of pure silver has a volume of 12.993 cm3, what would the mass? (136.3g) How many grams of tin would occupy 5.5 L, if it has a density of 7.265 g/cm 3? (4.0 x 104 g) What is the mass of a 350 cm3 sample of pure silicon with a density of 2.336 g/cm3? (820 g) Pure gold has a density of 19.32 g/cm3. How large would a piece of gold be if it had a mass of 318.97 g? (16.51 cm3) How many cm3 would a 55.932 g sample of copper occupy if it has a density of 8.92 g/cm 3? (6.270 cm3) The density of lead is 11.342 g/cm3. What would be the volume of a 200.0 g sample of this metal? (17.63 cm3) PERCENT ERROR % error = accepted value exp erimental value x 100 accepted value 10. Working in the laboratory, a student finds the density of a piece of pure aluminum to be 2.85 g/cm 3. The accepted value for the density of aluminum is 2.699 g/cm3. What is the student's percent error? (5.59%) 11. A student experimentally determines the specific heat of water to be 4.29 J/g x C o. He then looks up the specific heat of water on a reference table and finds that is is 4.18 J/g x C o. What is his percent error? (2.63%) 12. A student takes an object with an accepted mass of 200.00 grams and masses it on his own balance. He records the mass of the object as 196.5 g. What is his percent error? (1.75%) TEMPERATURE K = C + 273 13. 14. 15. 16. 17. 18. 250 Kelvin to Celsius 339 Kelvin to Celsius 17 Celsius to Kelvin 55 Celsius to Kelvin 89.5 Fahrenheit to Celsius 383 Kelvin to Fahrenheit C = K – 273 C = (F - 32) x 5/9 -23 oC 66 oC 290 K 328 K 31.9 oC 230. F 10 F = (C x 9/5) + 32 SPECIFIC HEAT CAPACITY Q = mc(T) where ΔQ is the heat energy put into or taken out of the substance m is the mass of the substance c is the specific heat capacity ΔT is the temperature differential. 19. How many calories of heat are required to raise the temperature of 550 g of water from 12.0 oC to 18.0 oC? (remember the specific heat of water is 1.00 cal/g x oC) = 3300 cal 20. How much heat is lost when a 640 g piece of copper cools from 375 oC, to 26 oC? (The specific heat of copper is 0.38452 J/g x oC) = 86 000 J 21. The specific heat of iron is 0.4494 J/g x oC. How much heat is transferred when a 24.7 kg iron ingot is cooled from 880 oC to 13 oC? = 9 600 000 J 22. How many grams of water would require 2.20 x 104 calories of heat to raise its temperature from 34.0 o C to 100.0 oC? (Remember the specific heat of water is 1.00 cal/g x oC)= 333 g 23. 8750 J of heat are applied to a piece of aluminum, causing a 56 oC increase in its temperature. The specific heat of aluminum is 0.9025 J/g x oC. What is the mass of the aluminum? = 170 g 24. Find the mass of a sample of water if its temperature dropped 24.8 oC when it lost 870 J of heat. (remember that 4.18 J = 1.00 cal) = 8.4 g 25. How many degrees would the temperature of a 450 g ingot of iron increase if 7600 J of energy are applied to it? (The specific heat of iron is0.4494 J/g x oC) = 38 oC 26. A 250 g sample of water with an initial temperature of 98.8 oC loses 7500 joules of heat. What is the final temperature of the water? (Remember, final temp = initial temp - change in temp) = 92 oC 27. Copper has a specific heat of 0.38452 J/g x oC. How much change in temperature would the addition of 35 000 Joules of heat have on a 538.0 gram sample of copper? = 170 oC 28. Determine the specific heat of a certain metal if a 450 gram sample of it loses 34 500 Joules of heat as its temperature drops by 97 oC. = 0.79 J/g x oC 29. 4786 Joules of heat are transferred to a 89.0 gram sample of an unknown material, with an initial temperature of 23.0 oC. What is the specific heat of the material if the final temperature is 89.5 o C? = 0.809 J/g x oC 30. The temperature of a 55 gram sample of a certain metal drops by 113 oC as it loses 3500 Joules of heat. What is the specific heat of the metal? = 0.56 J/g x oC 11 NAME:_________________________________ COURSE YEAR & SCHED:________________ SCORE:_________ DATE:___________ ACTIVITY 1.1 1. Given the following data, solve for the required values. TRIAL 1 METRIC ENGLISH SYSTEM(cm) SYSTEM (in) Length Width Thickness Length 1 13.3 6.2 6.5 5.3 2 13.4 6.4 6.3 5.2 Average Width 2.3 2.1 Thickness 2.4 2.3 Answer a)____________________ b)____________________ c)____________________ d)____________________ e)____________________ f)____________________ a) Area of the wooden block b) Experimental value c) Percentage error if the true value is 86.45 cm2 d) Volume of the wooden block e) Experimental value f) Percentage error if the true value is 538.39 cm3 2. Group the class into dyads and present a figure for each group to measure. Problem: What is the distance between points A and B following the arrow? Materials: Any measuring device or material found inside the classroom. Procedure: 1. Discuss within your group the possible ways of solving the problem. 2. Write down your proposed procedure. 3. Perform the activity and record the data gathered. 4. Show the procedure you followed to your instructor. 5. Fill in the table with appropriate data and do the necessary conversion of units stated below. Table 1 Name of Student 1. 2. 3. Average Table 2 Distance A to B mm Measurement cm M Note: Score will be based on percentage error. 12 km NAME:__________________________________________ COURSE YEAR AND SCHED.______________________ SCORE:_________ DATE: _________ ACTIVITY 1.2 1. Express each measurement to three significant figures in scientific notation. a) b) c) d) e) f) 8,567, 800,000,000 km 45.4236 g 0.0056231 L/mole 0.00000000000428 m/s 98.6700000 kg 99.98000 g/cm ________________________ ________________________ ________________________ ________________________ ________________________ ________________________ 2. Express each measurement in positional notation or exponential form. a) b) c) d) e) 2.35 x 105 g 33 000 000 mg 5.56 x 10 -8 mole 670 000 000 000 cg 100 000 000 cm3 ________________________ ________________________ ________________________ ________________________ ________________________ 3. Give the correct answer to the following using the rules in the operations with significant figures. 1. 286.05 m + 11.7 m + 3.66 m ________________________ 2. 35.77 L - 4.6 L ________________________ 3. 235 cm x 35 cm x 0.7cm ________________________ 4. 98.568 sec / 35 sec / 13.4 sec ________________________ 5. 395 km / 0.003 hr ________________________ 4. A basketball player is undergoing therapy after a mild surgery from his right leg due to bone translocation. During his exercise and physical examination, the following data were gathered. He stands 6 feet 3 inches tall. He weighs 194 pounds. He plays in a game for 35 minutes. He throws the ball with the speed of 100 miles per hour during fast breaks and he gains a body temperature of 102 degrees Fahrenheit during workout. a) How tall is the patient in (1) ______meter b) How much does he weigh in (1) ______kg (2) ______cm (2) ______g and (3) ______mm and (3) ______mg c) How long does he play in seconds? ______ d) How fast does he throw in (1) ______km/hr e) How hot is his body in (1) ______0C (2) ______ft/sec (2) ______K 13 (3) ______m/s NAME:__________________________________________ COURSE YEAR AND SCHED.______________________ SCORE:_________ DATE: _________ ACTIVITY 1.3 Solve the following problems correctly. Show all solutions. 1. A patient has a body temperature of 1040F. What is his temperature in Celsius? 2. Which patient has a higher fever, one with a temperature of 102.20F or one with a temperature of 39.00C? 3. Normal urine density is 1.025g/ml. What is the weight of a 100ml sample of urine? 4. An order for a medication reads: Give 0.25ml/kg body weight. How much medication should be given to a patient weighing 175 lbs? 5. For the following problems, refer to the given food label: a. In each serving, what is the amount of total fats in kilograms present? b. Determine the amount, in grams of cholesterol. c. How many μg of sodium is present? 6. Consider the following label on a vial of medication: Cefuroxime Pediatric Dosage 200mg/kg/day 14 a. How much of the antibiotic should be administered per day to an infant who weighs 14.7 lbs? b. If the medication is to be administered three times a day, how much medication should be given per dose? c. Compute for the total dosage in grams if the antibiotic is to be given for 7 days. 7. The doctor orders a 500 μg dose of a drug. Only 1mg tablet is on hand. How many would you give? 8. Consider the following medication order: Name: Pascual, Piolo Height: 5’8” Weight: 160lbs Medication Order: Meperidine IV q8h Dosage Instruction: 50mg/m2 a. Room-Bed: 100-A What is the patient’s height in inches? b. What is the patient’s weight in kilograms? c. What is the patient’s body surface area? d. Compute the amount of the drug to be administered to the patient. 9. A patient has been prescribed 15 mg of Diazepam. The tablet is available only at 0.005g dose. How many tablets should be given to the patient? 10. 800 ml of sodium chloride 0.9% (normal saline) is dripping into Mrs. Fernandez’ arm at 25 drops/min. The IV set delivers 20 drops/ml. How long will it take her to receive the infusion? 15 UNIT II: Matter and Energy Matter is anything that occupies space and has mass. Matter Pure Substances Element Mixtures Compound metal acid non-metal base metalloids salt Homogeneous solution Heterogeneous colloid suspension oxide PURE SUBTANCES Pure substances which consist of one particular kind of atom are homogeneous materials with definite chemical properties. ELEMENTS Element is a type of matter composed of atoms which all have exactly the same positive charge on their nuclei. All atoms of an element have the same atomic number. Classifications of elements: Metals Physical properties: Chemical properties: Usually solid at room temperature Ductile (can be drawn into sheets or wire without breaking) Malleable (can be hammered, pounded or pressed into different shapes without breaking) Good conductor of heat and electricity Show metallic luster when polish Combine with other metals to form an alloy Ex: bronze (Cu and Sn) and brass (Cu & Zn) React with non0metal to form ionic compound or salts Ex: NaCl, CaF2, K2O Lose electron forming positive ion (for base forming elements) Ex: Al, Mg, Ca, K 16 Non-metals Physical properties: Chemical properties: Metalloids or Semi-metals Properties: Seldom have metallic luster Tend to be colorless or brilliantly colored Often gases at room temperature Generally have low melting point and densities Serve as poor conductor of heat and electricity Are Brittle Combine with non-metals to form covalent compounds Ex: CO2, H2O, CH4 Gain electrons forming a negative ion (for acid forming elements) Ex: C, H, O, Br, S Have properties that lie between metals and non-metals Often look like metal but are brittle like non-metal Are neither conductor nor insulator but make excellent semi-conductor Ex: B, Si, As, Ge COMPOUNDS Are Pure substances Are made up of atoms of two or more elements combined in fixed ratios Are chemically combined elements May be broken or decomposed into simpler substances Classification of Compounds Acid comes from the Latin word acidus which means ‘sharp’ hydrogen compound whose hydrogen can be replaced by a metal the negative portion of the acid is a non-metal or an acid radical properties of acids: o have sour taste o turn blue litmus paper to red o react with certain metals to produce hydrogen o react with bases to produce salts and water classification of acids: o monoprotic acid ex: HNO3, HCl, HBr o diprotic acid ex: H2SO4, H2C2O4 o triprotic acid ex: H3PO4, H3AsO3 Base hydroxides of metals alkalis – soluble bases compound which forms hydroxyl group (OH) as the only negative group in the solution proton acceptor OH-1 radical 17 Salt properties of bases: o have bitter taste o have soapy or slippery feeling o turn red litmus paper to blue o react with an acid to produce salt and water o most metallic hydroxides are insoluble in water substance that consisst of a metal or a metallic radical combined with a non-metal or an acid radical an ionic compound consisting of a positive ion except hydrogen and a negative ion except hydroxide or oxide ion types of salts: o normal salt contains only a metal or a metallic radical, combined with a non-metal or an acid radical is neutral to litmus paper ex: NaCl o basic salt contains one or more OH radical reacts to litmus paper changing red to blue ex: Bi(OH)2 NO3 o acid salt compound in which a part of the hydrogen of the acid has been replaced by a metal reacts to litmus paper changing blue to red ex: NaHSO3 o double salt contains two metals combined with one radical ex: (NaAl(SO4))2 · 12 H2O Oxide compound which contains oxygen and only one other element kinds of oxides metallic oxide is a combination of a metal and oxygen considered as a basic anhydride base = water + basic anhydride ex: Na2O, CaO Na2O + H2O NaOH non-metallic oxide the element other than oxygen is a non-metal also called acid anhydride acid = non-metallic oxide + water ex: CO2 + H2O H2CO3 18 MIXTURE contains two or more substances that intermingle without being chemically combined has components that could be separated by either physical or chemical means has variable composition has constituents that retain their original identity since simple mixing has not changed their physical and chemical properties types of mixtures: o homogeneous mixture appears to be made up of only one phase to the naked eye ex: sugar solution, alloy, starch and flour o heterogeneous mixture components are easily identified or distinguished ex: rice and corn, sugar and sand, oil and water ways in separating mixtures o filtration o evaporation o decantation o magnetism o distillation o centrifugation o flotation o chromatography PROPERTIES OF MATTER Extensive property changes when the size of the sample changes ex: mass, volume, length, total charge Intensive property doesn’t change when some of the samples are taken away serves as clues in identifying unknown substances ex: temperature, color, hardness, taste, melting point, boiling point, pressure, molecular weight, density, malleability, ductility types of intensive property Physical property physical appearance o color, taste, odor, volume, mass physical changes o boiling point, melting point, freezing point Chemical property describes how a material reacts or fails to react with other materials reactivity o ability of a substance to combine readily with other substance combustibility o ability of a substance to combine with oxygen 19 stability o ability of a substance to resist change or inability to decompose under ordinary conditions deliquescence o ability of a substance to become wet when exposed to the air because it attracts and absorbs moisture from air. (ex. NaCl, ZnCl2) efflorescence o ability of a substance to become very dry, crisp and powdery when exposed to air because it loses its water of crystallization. (ex: washing soda) effervescence o ability of a substance to form bubbles or foams as it gives off gas. (ex: hydrogen peroxide) PHASES OF MATTER solids substances having definite volume and definite shape generally rigid materials and are in compact form types of solids crystalline substances o have definite arrangement and the atoms have definite relative positions o assume definite geometric shape or figure o have definite melting points o examples: table sugar, salt, diamonds amorphous substances o do not assume any definite form o have no definite melting points o are sometimes called “super cooled liquids o examples: wax, paraffin, glass, plastic liquids are substances having definite volume but no definite shape assume the shape of their containers are practically incompressible gases are substances having no definite shape and no definite volume are compressible have low densities plasma is an ionized gas which may result from the breaking of an atom or molecule of a gas when sufficient energy is supplied to it. contains free electrons and free positive ions, which are equal in number moving independently 20 CHANGES IN MATTER Physical change rearranges molecules but doesn’t affect their internal structures affects the state and appearance of matter no new substance is formed o boiling water o dissolving sugar in water o dicing potatoes processes o evaporation – liquid to gas o condensation – gas to liquid o freezing – liquid to solid o melting – solid to liquid o sublimation – solid to gas Chemical change results in the formation of a new chemical substance o iron rusting (iron oxide forms) o gasoline burning (water vapor and carbon dioxide form) processes o oxidation – process where oxygen is added, producing an oxide 2Na + O2 Na2O o Reduction – process where oxygen is removed from the substance 2HgO 2Hg + O2 o Neutralization – reaction of acid and base producing salt and water HCl + NaOH H2O + NaCl o Hydrolysis – reaction of salt and water producing acid and base KCl + H2O HCl + KOH o Fermentation – reaction caused by microorganisms producing alcohol and CO 2 Used in beer industries o Saponification – reaction between an alkali or base and fats and oils producing soap and glycerol Evidences of chemical change o Taking and giving off energy o Color/odor change o Evolution of gas o Formation of precipitate 21 Nuclear change is a change in the composition of nuclei of atoms is the fusion of hydrogen atoms to produce helium and energy nuclear fission o heavy nucleus splits into two much lighter nuclei, emitting several small particles at the same time o atomic bomb – uncontrolled fission exceeds the critical mass - (chain reaction) 1 kg of fissionable uranium – used bomb dropped on Hiroshima, Japan o Nuclear energy reactors – controlled fission Nuclear power plant generates heat to produce steam, which turns a turbine attached to an electric generator Heat is produced by splitting uranium nuclear fusion o two lighter nuclei combine to form a heavier one o ultimate source of nearly all the energy on Earth nuclear fusion in the sun deuterium + tritium helium + energy 1.7 x 109 kJ/mol of energy with no radioactive by-products ** Lise Meitner (1878-1968) Until very recently, this extraordinary physicist received little of the acclaim she deserved. Meitner worked in the laboratory of the chemist Otto Hahn, and she was responsible for the discovery of protactinium (Pa) and numerous radioisotopes. After leaving Germany in advance of the Nazi domination, Meitner proposed correct explanation of nuclear fission. In 1944 Hahn received the Nobel Prize in chemistry, but he did not even acknowledge Meitner in his acceptance speech. Today, most physicists believe Meitner should have received the prize. Despite controversy over names for elements 104 to 109, it was widely agreed that element 109 should be named meitnerium (Mt). 22 ENERGY every change in matter involves energy ability to do work. Kinetic Energy Energy possessed by a body in motion by virtue of its motion Potential Energy Energy possessed by a body at rest on the basis of its position, condition or composition Forms of Kinetic Energy: Forms of Potential Energy: Electrical Energy is the movement of electrical charges. It may operate electrical devices Chemical Energy is energy stored in the bonds of atoms and molecules. It is the energy that holds these particles together. Radiant Energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Thermal Energy, or heat, is the internal energy in substances––the vibration and movement of the atoms and molecules within substances. Nuclear Energy is energy stored in the nucleus of an atom––the energy that holds the nucleus together. Gravitational Energy is the energy of position or place. Sound Energy is produced when a force causes an object or substance to vibrate––the energy is transferred through the substance in a wave. CHANGES IN ENERGY 1. Exothermic change energy is given off it involves heat flow from the system to the surroundings example: combustion 2. Endothermic change energy is absorbed it involves heat flow from the surroundings to the system example: decomposition of water; melting of ice Enthalpy - a thermodynamic quantity that is the sum of the internal energy plus the product of the pressure and volume exothermic - decrease in the enthalpy of the system (H final < Hinitial) endothermic - increase in the enthalpy of the system (H final > Hinitial) melting of ice (heat flows into the ice from the surroundings) Entropy – a thermodynamic quantity related to the number of ways the energy of a system can be dispersed through the motions of its particles exothermic – heat lost by the system is gained by the surroundings endothermic – heat gained by the system is lost by the surroundings 23 LAWS OF MATTER AND ENERGY Law Proponent Law of Conservation Antoine Lavoisier of Matter Law of Conservation of Energy Gottfried Wilhelm Leibniz Law of Definite Proportion or Law of Constant Proportion Joseph Proust Law of Proportion John Dalton Multiple Theory Matter is neither created nor destroyed in any chemical reaction. Energy is neither created nor destroyed but can be transformed from one form to another. A pure compound is always made up or consists of the same element combined in the same proportions by mass. When two elements A and B form one compound, the amount of A that is combined in this compound with a fixed amount of B stand in small, whole-number ratio. Example 180 g glucose + 192 g oxygen gas 264 g carbon dioxide + 108 g water (372 g = 372 g) Calcium carbonate (CaCO3) Ca = 40 g = 40% C = 12 g = 12% O = 48 g = 48% 100 g 100% Carbon oxide I 57.1% oxygen 42.9% carbon Ratio: (57.1/42.9) = 1.33 Carbon oxide II 72.7% oxygen 27.3% carbon Ratio: (72.7/27.3) = 2.66 2.66 2 = (whole number ratio) 1.33 1 Mass fraction fraction by mass part of the compound’s mass contributed by the element dividing the mass of each element by the total mass of the compound Mass percent percent by mass fraction by mass expressed as a percentage 24 GAS LAWS Some Gases and their Uses GASES 1. carbon dioxide 2. dry ice 3. krypton 4. xenon 4. liquid helium 5. Argon 6. Argon-nitrogen mixture 7. steam or gaseous water 8. ozone USES Used as a refrigerant Insufflation gas for minimal invasive surgery to enlarge and stabilize body cavities for better visibility of the surgical field For cryotherapy Used in preserving, freezing, and transporting food Used to preserve and ship biological samples. Used by cosmetic surgeons to freeze warts for easy removal. Used in lasers and photography Used in coagulation of retina (krypton laser) Used in anesthetics Used in magnetic resonance imaging (MRI) Used as a semi-conductor Used for treatment of benign eyelid tumor Used in electric light bulbs Used to power electric generators Used to protect man from too much exposure to the sun’s ultraviolet rays Manifests bactericidal, virucidal and fungicidal actions Has the capacity to stimulate blood circulation and the immune response The Kinetic Molecular Theory of Gases 1. Particles of gases are constant, random, and straight-line motion. 2. Molecules of a gas are separated by great distances which makes the gas mostly empty space. 3. Molecules collide with one another and with the walls of their container. 4. Each molecule acts independently of all the others. 5. Individual molecules upon collision may or may not gain energy. Atmospheric Pressure it is the force exerted by air upon a given volume of matter measured by a barometer (Evangelista Torricelli) measured by a manometer 1 atmosphere (1 atm) = 101.3 kPa 14.7 lb/in2 76 cmHg 760 mmHg 760 torr 1.01325 bar 1013.25 mb Standard Temperature and Pressure (STP) 0 °C (273 K) 1 atm 25 Physical Properties indefinite shape and volume gases exert pressure low density diffusion Gas Laws Boyle’s Law Relation of volume to pressure at constant temperature Robert Boyle “At constant temperature, the volume of a confined gas is inversely proportional to pressure”. P α 1/V P = k/V PV = k P1V1 = P2V2 Example: a. If the volume of a gas is 8.0 L under a pressure of 4.2 atm, what would be its volume if the pressure were increased to 7.4 atm? i. Given: Required: V2 1. P1 =4.2 atm 2. V1 = 8.0 L 3. P2 = 7.4 atm ii. Solution: 1. P1V1 = P2V2 P1V 1 P2 4.2 x8.0 4.54 L 3. V2 = 7.4 2. V2 = b. A sample of oxygen occupies 18.5 L under a pressure of 800 torr. At what pressure would it occupy 23.4 L if the temperature did not change? c. A gas at 1 atm expands to a final volume of 6.45 L having a final pressure of 600 atm. What is the initial volume of the gas? Charles’ Law Relation of volume to temperature at constant pressure Jacques Alexandre Cesar Charles “The volume of a confined gas is directly proportional to temperature when pressure is held constant”. V α T V = kT V/T = k V1 V 2 = T1 T 2 Example a. A sample of nitrogen occupies 230 mL at 290 K. At what temperature in K would it occupy 340 mL if the pressure is held constant? i. Given: Required: T2 1. T1 = 290 K 2. V1 = 230 mL 3. V2 = 340 mL 26 ii. Solution: V1 V 2 = T1 T 2 T 1V 2 2. T2 = V1 290 x340 3. T2 = 428.70 L 230 1. b. A tank contains 600 L of oxygen at 34 °C. What will be the final volume if the temperature is increased to 40 °C? c. What is the initial volume of a 45 mL in an inflated balloon at 25 °C if the final temperature is 39.6 °C? Combined Gas Laws Boyle’s Law and Charles’ Law “The volume occupied by a given amount of gas is proportional to the absolute temperature divided by the pressure”. T T V = P P P1V 1 P 2V 2 T1 T2 V α Examples: a. A sample of neon occupies 120 L at 34 °C under a pressure of 900 torr. What is its volume at standard temperature and pressure (STP)? iii. Given: Required: V2 1. T1 = 34 °C + 273 = 307 K 2. V1 = 120 L 3. P1 = 900 torr 4. T2 = 273 K 5. P2 = 760 torr iv. Solution: P1V 1 P 2V 2 T1 T2 P1V 1T 2 2. V2 = P 2T 1 900 x120 x 273 126.37 L 3. V2 = 760 x307 1. b. What is the volume of methane at 273 K and 760 torr, if its original volume at 300 K and 769 torrs is 40 cc? 27 Gay Lussac’s Law of Combining Volumes Joseph Louis Gay Lussac “Gases combine in simple and definite proportions by volumes or gases react with one another in volume ratios of small whole numbers” o 2 H2 + O2 2 H 2O 2L 1L 2L Avogadro’s Law Amadeo Avogrado “At the same temperature and pressure, equal volumes of all gases contain the same number of molecules”. 1 mol gas = 22.4 L at STP V α n V = kn V/n = k V1 V 2 n1 n 2 Dalton’s Law of Partial Pressures John Dalton “The total pressure exerted by a mixture of ideal gases is the sum of the partial pressures of those gases”. Ptotal = PA + PB + PC + ….. The Ideal Gas Law Boyle’s Law, Charles’ Law and Avogadro’s Law PV = nRT R (universal gas constant) = 0.082057 L atm mol K Examples: a. What pressure in atm is exerted by 7.8 mol of Xe in a 1.2 L flask at 287 K? v. Given: Required: P 1. n = 7.8 mol 2. V = 1.2 L 3. T = 287 K 4. R = 0.082057 L atm mol K vi. Solution: 1. PV = nRT nRT V 7.8 x0.082057 x 287 153.08 atm 3. P = 1.2 2. P = b. What is the volume of a gas balloon filled with 3 moles of He when the atmospheric pressure is 790 torr and the temperature is 30 °C? c. Nitric acid, a very important industrial chemical, is made by dissolving the gas nitrogen dioxide NO2 in water. Calculate the number of moles needed at 2 atm and 340 K. 28 Graham’s Law of Diffusion The rates of effusion or diffusion of two different gases are inversely proportional to the square roots of their molar masses Diffusion is the movement of a fluid from an area of higher concentration to an area of lower concentration. Effusion is the escape of gas in its container RgasA = RgasB MgasB MgasA Where: R is the rate of diffusion of effusion of gas A or B M is the molar mass of either gas A or gas B The rates of diffusion of two gases is inversely proportional to the square roots of their densities RgasA = RgasB DgasB DgasA Where: R is the rate of diffusion of effusion of gas A or B D is the density of either gas A or gas B Example: Complete the relative rates of H2 and CO2 through a fine pinhole. Solution: Molecular weight of H2 = 2 amu Molecular weight of CO2 = 44 amu RgasA = RgasB MgasB MgasA RH 2 = RCO 2 MCO2 MH 2 RH 2 = RCO 2 44 22 Answer: RH2 = 4.69 times the rate of RCO2 NAME:__________________________________________ 29 SCORE:_________ COURSE YEAR AND SCHED.______________________ DATE: _________ ACTIVITY 2.1 MATCHING TYPE D O O O O O O O O O O E O O O O O O O O O O Match Column I with Column II. Shade the circle that best corresponds to your answer (one per number). Erasures and superimpositions will invalidate correct answers. A O O O O O O O O O O B O O O O O O O O O O C O O O O O O O O O O Column I 1. Ag 2. aluminum 3. baking soda 4. distilled water 5. ice cream 6. jelly 7. mineral water 8. peanut butter 9. styrofoam 10. table sugar Column II A. colloid B. compound C. element D. solution E. suspension A O O O O O B O O O O O C O O O O O Column I 11. burning of a candle 12. condensation of water vapor 13. radioactive decay of uranium 14. cutting of diamonds 15. fireworks (pyrotechnics) Column II A. nuclear change B. physical change C. chemical change A O O O O O B O O O O O C O O O O O D O O O O O Column I 16. electronegativity 17. flammability 18. temperature 19. volume 20. acidity Column II A. chemical property B. both C. physical property D. neither A nor C A O O O O O B O O O O O C O O O O O D O O O O O E O O O O O Column I Column II 21. thermal equilibrium A. Law of Conservation of Mass 22. conservation of energy B. Second Law of Thermodynamics 23. zero heat, maximum entropy (disorder) C. E = mc2 24. matter can’t be created D. Zeroth Law of Thermodynamics 25. mass is converted to an amount of energy E. First Law of Thermodynamics A O O O O O B O O O O O C O O O O O D O O O O O E O O O O O Column I 26. bird sitting on a tree branch 27. battery 28. mp3 file playing 29. nuclear explosion 30. friction in a roller coaster Column II A. kinetic to electrical energy B. potential energy C. mechanical to thermal energy D. electrical to sound energy E. kinetic to radiant energy 30 PROBLEM SOLVING Show all derivations and solutions in detail for full credit of points. Enclose/Emphasize all final answers at the end of every solution. Round off final answers to 2 SD. ___________________1. A sample of a gas occupies 360 ml under a pressure of 0.75 atm. If the volume is decreased to 56 ml, what is the final pressure, the temperature remaining constant? ___________________2. A sample of a gas has a volume of 79.5 ml at -45 °C at 1 atm. What volume will the sample occupy at -25 °C at 1 atm? ___________________3. A 20-liter container is filled with a gas to a pressure of 10 atm at 0°C. At what temperature (in °C) will the pressure in the container be 2.5 atm? ___________________4. P1 = 3.48 atm, V1 = 1.68 L, T1 = 994.2 K, P2 = 4,142 torr, V2 = 6,060 mL, T2 = ____ in °C Solve for the unknown values in the table below: P V 5. 2.00 atm _____li 6. 456 torr 1.00 li 7. 3382 mm Hg 50.00 ml 8. _____Pa 1250 cc n 1.5 mol _____mol 0.0105 mol 2.6 mol 31 T 100 °C 100 °K _____°K 75 °C NAME:__________________________________________ COURSE YEAR AND SCHED.______________________ SCORE:_________ DATE: _________ ACTIVITY 2.2 1. Use the general gas law to find the volume of air exhaled under the following conditions: P1 = 98 kPa P2 = 105 kPa 0 T1 = 25 C T2 = 350C V1 = 500 ml V2 = ? Focus Questions: 1. Define ventilation. Explain how air moves in and out of the lungs, using the concept of pressure. 2. What is meant by negative pressure in the lungs? How does intrapleural pressure prevent the lungs from collapsing? 3. What is diffusion? Use your definition to account for the movement of gases to and from the blood through the walls of the alveoli and capillaries? What factors will affect this process? 4. Why is the presence of a surfactant in the fluids of the alveoli important? 5. Explain the process by which oxygen is transported in the blood and released to the cells in the body? 32 UNIT III: Atomic Structure Atom comes from the Greek word “atomos” which means “uncut” or “indivisible” Atomic Theory Scientists Democritus Aristotle Daniel Bernoulli John Dalton Contribution He proposed that ‘matter is made up of tiny, indivisible atoms’. He did not accept the theory of Democritus. He proposed the 4-element theory making up matter. He attempted to explain the behavior of matter quantitatively; Dalton’s Atomic Theory may be summed up as follows: An element is composed of extremely small, indivisible particles called atoms. All atoms of a given element have identical properties that differ from those of other elements. Atoms cannot be created, destroyed, or transformed into atoms of another element. Compounds are formed when atoms of different elements combine with one another in small whole-number ratios. The relative numbers and kinds of atoms are constant in a given compound. Atomic Models: Dalton’s Model 1808 Thomson’s Model 1890 Rutherford’s Model 1911 Electron Cloud Model 33 Lord Kelvin’s Model 1900 Bohr’s Model 1913 Men who contributed in the Development of Modern Atomic Concept Scientists Joseph Jon Thomson Wilhelm Konrad Roentgen Robert Millikan Eugen Goldstein Sir James Chadwick Henri Becquerel Ernest Rutherford Max Planck Neils Bohr Henry Moseley Sommerfield Louis de Broglie Erwin Schrödinger Weiner Heisenberg Plucker Contribution He discovered the electron using the cathode ray tube. He named his atomic model as ‘raisin or plum pudding model’. He discovered the x-rays (penetrating rays without mass or charge) using the cathode ray tube. He discovered the charge of an electron which is 1.60 x 10-19 coulomb using x-rays. He discovered the protons using the canal ray tube. He studied the alpha particles in beryllium, which lead to the discovery of neutron. He pioneered the study on radioactive rays together with Marie Sklodowska Curie and Pierre Curie. He perceived the atom as a miniature solar system. He used the alpha scattering apparatus leading to the discovery of the nucleus. alpha (α) o +2, stopped by a thin sheet of paper, injure normal cells in the body Beta (β) o -1, stopped by a 1 cm thick of aluminum foil, harmful to the body Gamma (γ) o No charge, stopped by lead, cause mutations He described the radiant energy as consisting of quanta. He developed a theory that an electron in the atom gains or loses energy by absorbing or emitting energy in orbits. He noted that the number of positive charges increases from atom to atom by single electronic unit. He introduced sub-levels and assuming electrons travel in an elliptical as well as circular orbits. He extended the particle-wave duality concept that matter must be both as particle and a wave (matter waves). He developed the equation that relates the wavelength of an electron to its energy, which described the probability that an electron will be at a certain point in space He stated that it is impossible to pinpoint or to determine accurately both the momentum and the position of the electron simultaneously. (referred to as the Uncertainty principle) He experimented the cathode by a steam of high speed of electron. 34 Modern Atomic Theory The modern atomic theory involves the small nucleus and the three elementary particles called the protons, electrons, and neutrons. The nucleus contains the protons and the neutrons surrounded by an electron cloud. Atomic particle Electron Proton Neutron actual mass (g) 9.110 x 10-29 1.673 x 10-24 1.675 x 10-24 Mass Number (A) - “massenzahl” A Z Electrical charge (C) relative mass (amu) -1 1/1837 (- 1.602 x 10-19) +1 1 (+ 1.602 x 10-19) 0 1 X symbol of element (X) Atomic Number (Z) – “atomzahl” A = p + n e = p = Z Element A B C A 15 Z 8 p e 6 42 18 24 35 n Nucleons Name of the protons and neutrons inside the nucleus Ions Electrically charged atoms (positive and negative ions) Isotopes Atoms having different atomic weights or mass but of the same atomic number Frederick Soddy Element Hydrogen Symbol 1 1H 2 1H Mass (amu) Percent abundance 1.0078 99.985 2.0141 0.015 3.0160 negligible 12.00 98.89 Average atomic mass 1.0079 3 1H Carbon 12 6C 12.011 13 6C Oxygen 13.003 1.11 15.995 99.759 16.995 0.037 34.969 75.77 16 8O 15.999 17 8O Chlorine 35 17Cl 35.453 37 17Cl 36.966 Separation of Isotopes Centrifuge Thermal diffusion Electrolysis Fractional distillation 36 24.23 Radioisotopes Are artificial radioactive isotopes Discovered by Irene and Frederic Joliot Curie Are prepared by the bombardment of naturally occurring atoms Radioisotopes 1. Iodine – 131 Iodine – 123 2. Strontium – 90 3. Cobalt – 59 Cobalt - 60 4. Thallium – 201 5. Chromium - 151 6. Boron - 10 7. Fluorine – 18 8. Strontium-89 Samarium 153 Rhenium-186 9. Phosphorus - 32 Uses Diagnostic testing of thyroid gland functions Treatment of small lesions Radiation therapy of most tumors/cancerous cells Studying defects in vitamin B12 absorption Myocardial imaging Detection and prognosis of coronary artery disease Determining the flow of blood through the heart Important in the diagnoses of anemia Detection of malignant tumor cells in the brain Cardiac and brain imaging Relief of cancer-induced bone pain Controlling the excess Polycythemia vera, an excess of red blood cells is produced in the bone marrow 10. Technetium - 99 Imaging the skeleton and heart muscle in particular, but also for brain, thyroid, lungs (perfusion and ventilation), liver, spleen, kidney (structure and filtration rate), gall bladder, bone marrow, salivary and lacrimal glands, heart blood pool, infection and numerous specialized medical studies 11. Bismuth - 213 Targeted alpha therapy (TAT), especially cancers 12. Copper – 64 Studying genetic diseases affecting copper metabolism, such as Wilson's and Menke's diseases 13. Dysprosium - 165 Aggregated hydroxide for synovectomy treatment of arthritis 14. Holmium - 166 Diagnosis and treatment of liver tumors 15. Iron - 59 Studying of iron metabolism in the spleen 16. Selenium – 75 Inn the form of seleno-methionine for studying the production of digestive enzymes 17. Sodium – 24 Studying of electrolytes within the body 18. Xenon – 133 Pulmonary (lung) ventilation studies 19. Ytterbium – 169 Cerebrospinal fluid studies in the brain 20. Yttrium – 90 Cancer brachytherapy and as silicate colloid for the relieving the pain of arthritis in larger synovial joints Source: James R. Fromm (jfromm@3rd1000.com); http://www.bookrags.com; Radioisotopes in Medicine. World Nuclear Association (http://www.world-nuclear.org) 37 Quantum Theory Study of the discrete nature of phenomena at the atomic and subatomic levels Quanta – indivisible units of energy Plank’s Theory Max Plank (German) Explained why spectra of radiation changes with the temperature Photon – a quantum or packet of electromagnetic radiation o Photoelectric effect – Einstein o Compton effect – Arthur Compton Dualistic Nature of Light Louis de Broglie (French) Light is both a wave and a particle Matter waves – matter behaves like a wave and that light waves behave like particles of matter The Uncertainty Principle Werner Heisenberg The actual position and velocity of the particle cannot both be determined at the same time The Present Day Atom Erwin Schrödinger Mathematic theory of wave mechanics Wave function or orbitals Electron cloud Energy level Energy shell Corresponds to the period of an element in the periodic table A group of atomic orbitals that have the same value for (n), the principal quantum number Sub-level A division of an electron shell An electron shell may hold two or more orbitals 1. s (sharp) spherical shape 1 orbital (2 electrons) 2. p (principal) dumbbell shaped px, py, pz (3 orbitals) (6 electrons) 3. d (diffuse) four-leaf clover, an hour glass and a ring 5 orbitals (10 electrons) 4. f (fundamental) complex shapes 7 orbitals (14 electrons) 38 Valence electron Electron found in the outermost shell in the ground state Valence shell The outermost energy level Orbital A region around the nucleus of an atom where an electron with a given energy is likely to be found Principal Energy n=1 n=2 n=3 n=4 Sublevels 1s 2s, 2p 3s, 3p, 3d 4s, 4p, 4d, 4f Orbitals 1 8 27 64 Max Electrons 2 8 18 32 Quantum Numbers 1. principal quantum number (n) o refers to the main energy levels o K, L, M, N, O, P, Q 2. azimuthal quantum number (l) o describes the way the electron moves around the nucleus o describes the orbital shape o s, l = 0; p, l = 1; d, l = 2; f, l = 3 3. magnetic quantum number (m) o describes the possible orientation in space of the electrons in a magnetic field o s, m = 0 (no effect on a magnetic field) o p, m = -1, 0, +1 (for px, py, and pz) o d, m = -2, -1, 0, +1, +2 (5 d orbitals) o f, m = -3, -2, -1, 0, +1, +2, +3 (7 f orbitals) 4. spin quantum number (s) o describes the way the electron spins or rotates on its own axis as it moves about the nucleus o +1/2 spin (clockwise direction) o -1/2 spin (counterclockwise direction) Parallel spins – both are cw or cc Opposite spins – one cw and the other cc Paramagnetism – property of a substance to be attracted by a magnet (unpaired electrons) Diamagnetic – repelled by a magnet (paired electrons) 39 Example 1. 2p4 n = 2; l = 1; m = -1; s = +1/2 2. 3p3 n = 3; l = 1; m = +1; s = -1/2 3. 3d6 n = 3; l = 2; m = -2; s = +1/2 Electron Configuration Orderly distribution of electrons among the orbitals of an atom Mnemonic Device Source: http://www.mpcfaculty.net/mark_bishop/memory_aid_e_config.jpg Ground State Lowest, most stable energy state of the atom Aufbau Principle German word “aufbaue” – to build up Electrons are added one at a time to the lowest energy orbitals Pauli Exclusion Principle No two electrons can occupy the same quantum state simultaneously in an atom o An orbital can hold a maximum of 2 electrons o The electrons can occupy the same orbital if they spin in opposite direction clockwise (upward arrow) counterclockwise (downward arrow) Hund’s Rule When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins Second electrons then add to each orbital pairing the spins of the first electrons 40 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 3.1 Given the atomic number of the following elements: A. Write the orbital diagram of the outermost configuration. B. Write the electronic configuration. C. Determine the family and period where the element is located. 1. A12 Orbital diagram: ____________________________________________________________ Electronic configuration: ______________________________________________________ Family: __________ Period: __________ 2. B23 Orbital diagram: ____________________________________________________________ Electronic configuration: ______________________________________________________ Family: __________ Period: __________ 3. C30 Orbital diagram: ____________________________________________________________ Electronic configuration: ______________________________________________________ Family: __________ Period: __________ 3. C67 Orbital diagram: ____________________________________________________________ Electronic configuration: ______________________________________________________ Family: __________ Period: __________ 3. C80 Orbital diagram: ____________________________________________________________ Electronic configuration: ______________________________________________________ Family: __________ Period: __________ 41 Valence Electron Electrons in the outermost energy level Determines the chemical properties of elements Lewis Dot Structure Gilbert Lewis Noble gas configuration o Rule of Two or Duet Rule o Octet Rule Consists of the element’s symbol surrounding dots to represent the number of valence electrons Examples: Phosphorus Chlorine Arsenic Chemical Bonds 1. Ionic Bond Transferring of electrons Metal donates the electron to a non-metal Metal + non-metal Properties of Ionic Compounds o Are solid with high melting point ( › 400°C) o Are soluble in polar solvents o Conduct electricity when in aqueous solution or in molten state Examples: Source: www.hcc.mnscu.edu/.../V.12/LiF_ionic_bond.jpg 2. Covalent Bond Sharing of electrons Non-metal + non-metal o Single bond (H2O, CH4) o Double bond (O2, CO2) o Triple bond (N2) Properties of Covalent Compounds o Are usually gas, liquid or solid with low melting points ( < 300°C) o Mostly are soluble in non-polar solvents 42 Examples: a. Cl2 and H2 b. O2 c. N2 3. Metallic Bond Is the force of attraction that holds metals together Consists of the attraction of the free-floating valence electrons for the positively charged metal ions Explains many physical properties of metals o Metals are good conductors of electricity o Metals are ductile o Metals are malleable 43 4. Intermolecular Forces of Attraction Are the forces of attractions that exist between molecules in a compound Cause the compound to exist in solid, liquid, or gas; and affect the melting and boiling points of compounds as well as the solubility of one substance in another Also called Van der Waals forces (Johannes van der Waals 1837-1923) Types of Intermolecular Forces of Attraction Dispersion forces Weakest of all molecular interactions among non-polar molecules (H2, Cl2) The more electrons that are present in the molecule, the stronger the dispersion forces Dipole to dipole interaction Occurs between polar molecules The partial positive charge on one molecule is electrostatically attracted to the partial negative charge on a neighboring molecule Hydrogen bonds Are the strongest of the intermolecular forces Important in determining the properties of water and biological molecules like protein Occur between molecules from hydrogen being covalently bonded to either fluorine, oxygen or nitrogen 44 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 3.2 I. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Fill-in the Blanks: Write the word or group of words on the blank to complete each sentence. Atom comes from the ________________ word ‘atomos’ which means uncut or indivisible. Daniel Bernoulli attempted to explain the behavior of matter _______________. _______________ is the study of the attraction of materials to charged bodies. JJ Thomson discovered the electron using _______________. Goldstein used the _______________ in discovering proton. Cations are ______________ charged ions. The element hydrogen has _____________ isotopes. The Swedish chemist, _______________, used the first one or two letters of the name of the element for its chemical symbol. _______________ is the Latin word for mercury. _______________ proposed the particle-wave nature of matter. II. Fill-in the table with the correct information: Element Mass Number Atomic Number 1. B 12 7 2. L 3. Es 36 4. S 10 5. U 45 P e 9 n 12 24 9 15 III. Provide the (a) electronic configuration of the following elements. Illustrate the (b) orbital diagram of the outermost configuration and determine its (c) set of quantum numbers. (30 pts) 1. A6 a) ______________________________________________________________________ b) ______________________________________________________________________ c) n = _____ l = _____ m = _____ s = _____ 2. B10 a) ______________________________________________________________________ b) ______________________________________________________________________ c) n = _____ l = _____ m = _____ s = _____ 3. C17 a) ______________________________________________________________________ b) ______________________________________________________________________ c) n = _____ l = _____ m = _____ s = _____ 45 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 3.3 Illustrate the Lewis Dot and Structural Formulas (Cationic kernels are underlined). Then identify the type (and subtype, if applicable) of the chemical bond. Minimize erasures. KCN carbon tetrachloride O2 water molecule nitrogen gas chlorine gas oxygen gas CH4 Structural Formula Lewis Dot Formula Structural Formula Lewis Dot Formula Structural Formula Lewis Dot Formula Ca(OH)2 46 UNIT IV: The Periodic Table Chemical Symbols Swedish chemist J.J. Berzellius (1779 – 1848) used the first one or two letters of the name of the element o C, H, O, N, S, I, Al, Br, Ca, Co, Si, Ti Derived from the name of the discoverer o Lawrencium (Lr) o Einsteinium (Es) o Fermium (Fm) o Mendelevium (Md) Name of gods o Thorium (Th) o Vanadium (V) From place of the founder o Francium (Fr) o Americium (Am) o Californium (Cf) o Europium (Eu) o Gallium (Ga) o Germanium (Ge) o Polonium (Po) From Latin words o Antimony o Copper o Gold o Iron o Lead o Mercury o Potassium o Silver o Sodium o Tin Stibium Cuprum Aurum Ferrum Plumbum Hydrargyrum Kalium Argentum Natrium Stannum Sb Cu Au Fe Pb Hg K Ag Na Sn 47 Periodic Table table of the chemical elements arranged to show patterns of recurring chemical and physical properties one way of arranging known elements and provides a possible way of determining elements yet to be discovered Development of the Periodic Table Scientists Contribution Johannes Dobereiner He arranged the elements by ‘triad’ according to order of physical properties. Examples: Ca, Ba, Sr / Cl, I, Br / S, Te, Se / Fe, Co, Ni John Newlands He arranged the elements by ‘law of octaves’ according to order of increasing atomic weights. Examples: H, F, Cl, Co&Ni, Br, Pd, I, Pt&Ir Li, Na, K, Cu, Rb, Ag, Cs, Tl Lothar Meyer He arranged the elements according to periodic trends. Melting points, boiling points, and chemical activities Dmitri Mendeleev He arranged the elements in order of increasing atomic mass. Henry Moseley He arranged the elements in order of atomic number giving rise to the ‘modern periodic table’. Modern Periodic Table Periods – seven horizontal rows Groups or Families – eighteen vertical columns o Representative elements – Group 1A through Group O o Transition elements – Group B elements o Lanthanides o Actinides Periodic Law The physical and chemical properties of the elements are periodic functions of their atomic number Uses of the Periodic Table 1. The periodic table is a helpful tool used by scientists and students to find the structured sequence in terms of physical and chemical properties which identify an element. 2. If a person knows the main properties of each of the groups in the periodic table and how chemical properties vary within a group, he or she can predict the properties of any particular element with a reasonable degree of confidence. 48 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 4.1 Puzzle: Encircle the names of the element symbols in the puzzle. F R A N C I U M U I N A R U C R A R I O R K Y Y N T A O O A E D G T P O L O N I U M B X R B I O R O N W L R R C A O Y B O U N A T I N D R A L M R G O P M T Y Q Y I R T T A I O E N O M A G N E S I U M P L N N A E Y U E X Q I N N A S O Y M A Y Z I N C C L G G N E V T A M R A P I U B V S S I E E O B U U P L C I N E O T L N U S A I C P K K E A R S E N I C M I R R H I E W J A F N A D A I T T E E M L M D A A W R O N U K T M R P F P O T A S S I U M A Y 1. Fr 2. Hg 3. W 4. Mg 5. C 6. Co 7. Ar 8. Zn 9. Po 10. K 11. I 12. Ni 13. B 14. Ag 15. As 49 16. O 17. Os 18. Sn 19. Y 20. U Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 4.2 Case Study: Mrs. Anne Curtis is in her late 50’s. On admission she had a weight of 175Kg. She has a history of adult-onset diabetes mellitus. She is in hospital recovering from a septic ulcer on her left foot. A glucose tolerance test administered on admission indicated a level of glucose in the blood of over 150mg/mL indicating loss of insulin control. One reason for this seems to be her poor attention to diet. On her chart are the following information, placed there for reference by student nurses: Clinical note for Anne Curtis: Nursing care for this patient would involve continuous monitoring of such chemistry-related values of serum osmolality, electrolytes, glucose, hemoglobin, hematocrit, and urine ketones. Also, there may be a need to administer prescribed regular insulin when serum glucose falls within the range of 250-800mg/dL. 1. Explain how Anne Curtis’ dietary treatment is helping to deal with her diabetes and her obesity. Be specific in your discussion, referring to insulin, glucose, and the organic molecules in her diet. 2. Anne Curtis is ordered 36 units of ‘Actfast’ insulin each morning and 18units each night. What are the two volumes you would give if the 10mL vial contains 100U/mL. 50 Periodic Trends Property Atomic Radius Description Distance of the electron cloud from the nucleus Trend Family – increases Period - decreases Family – decreases Period – increases Ionization Energy Energy required to remove an electron from an atom Nuclear charge – the larger the nuclear charge, the greater is the ionization energy Shielding effect – the greater the shielding effect, the less is the ionization energy Atomic size – the bigger the atom, the lesser is its ionization energy Sub-energy level – an electron from a full or half full sublevel requires additional energy to be removed Electron Affinity Energy required to attract an additional electron Metals – low electron affinity Non-metals – high electron affinity Family – decreases Period – increases Electronegativity Ability of an atom to attract a shared pair of electrons in a chemical bond Family – decreases Period – increases Ionic radius Distance between the nuclei of two like atoms after gaining or losing electrons Family – increases Period - decreases Metallicity Tendency of an element to lose electrons forming positive ion Family – increases Period – decreases Non-metallicity Tendency of an element to gain electrons forming negative ion Family – increases Period - increases The Beneficial and Harmful Elements to the Environment Question: What elements are harmful to living organisms and how do they get into our environment? Trace essential elements such as fluorine, copper, selenium, molybdenum, and others can be hazardous to living organisms if present at high levels. Nonessential heavy metals such as arsenic, lead, mercury, cadmium, chromium are usually toxic to organisms as much lower levels than trace essential elements. Depending on the association that these nonessential elements may form with natural geologic materials such as organic matter, other elements or minerals, and adsorbers (such as clays), these elements can range from being safe to being extremely toxic. (http://geology.er.usgs.gov/eastern/environment/environ.html) 51 What harmful elements are contained in auto exhaust gas? (01/17/2004) Auto expel large amount of carbon monoxide, hydrocarbon, nitro-oxide, fine articles and sulfide, etc. All these primary pollutants will form such secondary pollutants as actinological fume and acid disposition, etc. Out of the pollutants, carbon monoxide can put people in a state of oxygen deficiency, and result in chronicle intoxication with long time contact; hydrocarbon is the substance incurring cancer; and nitrooxide will do harm to respiratory system and immune system of human body. Lead pollution will be brought about after petroleum-containing lead is burned and 85% of lead are let out into air. In the past half century, amount of lead released into air after auto exhaustion has reached millions of tons, which has become a pollution source globally. Lead will do harm to a lot of human organs and systems such as deterioration of intelligence, kidney damnification, infertility and high blood pressure. Lead pollution in air does the most harm to children. If amount of lead increases in children, it can result in deterioration of intelligence, and impose negative impact on growth of children, even bring about some diseases. According to some research, amount of lead in blood increases by 10gramma per deciliter, and average IQ of children will decrease 2.5. (Copyright 2007 Shanghai Municipal Government All Rights Reserved .) 52 UNIT V: Chemical Nomenclature of Inorganic Compounds and Chemical Equations Chemical Nomenclature Steps in writing formulas: 1. Write the symbol of the positive particle or cation first before the symbol of the negative particle or anion. Example: Na+ Al3+ O2F2. Criss-cross the valence numbers, disregarding the sign, so that the charge of the cation becomes the subscript of the anion and the charge of the anion becomes the subscript of the cation. Example: Na+ + FK- + O2Na1 F1 K2O1 a. If the subscript is 1, it is no longer written. Example: NaF K 2O b. If the subscript of both cation and anion are the same, omit writing the subscripts. Example: Mg2+ + S2MgS c. Reduce the subscript to the simplest whole number ratio. Example: W6+ + O2W2O6 ------- WO3 d. When the polyatomic ion needs a subscript, enclose it first with a parenthesis. If the original polyatomic ion already contains a parenthesis, use a bracket. Example: Al3+ + Cr2O72B3+ + Fe(CN)64Al2(Cr2O7)3 B4[Fe(CN)6]3 Naming Chemical Formulas Rules for naming inorganic compounds 1. Binary compounds containing a metal and a non-metal Give the name of the cation first followed by the anion Transition metals a. Old/traditional system i. FeBr2 – ferrous bromide ii. FeBr3 – ferric bromide b. Stock system i. FeBr2 – iron (II) bromide ii. FeBr3 – iron (III) bromide 53 Naming Ions Using the Stock System and Old System Ion Stock System 2+ Fe Iron (II) Fe3+ Iron (III) Cu+ Copper (I) 2+ Cu Copper (II) Sn2+ Tin (II) 4+ Sn Tin (IV) 2+ Pb Lead (II) Pb4+ Lead (IV) Hg+ Mercury (!) Hg2+ Mercury (II) Au+ Gold (I) 2+ Au Gold (III) Old System Ferrous Ferric Cuprous Cupric Stannous Stannic Plumbous Plumbic Mercurous Mercuric Aurous Auric 2. Binary compounds containing two non-metals Use prefixes to indicate the numbers of atoms present Mono is never used in the first element o NO2 – nitrogen dioxide o P2O5 – diphosphorus pentaoxide 3. Binary acids Non-oxygen acids Use the prefix hydro followed by the anion and the word acid added at the end o HCl – hydrochloric acid o H2S – hydrosulfuric acid 4. Ternary compounds Compounds containing more than two elements Give first the name of the cation followed by the anion o K2SO4 – potassium sulfate o NH4NO3 – ammonium nitrate 5. Ternary acids Oxyacids -ite (ous ending) -ate (ic ending) o HNO2 – nitrous acid (hydrogen + nitrite) o HNO3 – nitric acid (hydrogen + nitrate) o HClO2 – chlorous acid (hydrogen + chlorite) o HClO3 – chloric acid (hydrogen + chlorate) 54 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 5.1 I. Name the following compounds. (10 pts) Traditional System 1. CuBr ________________________ Stock System _____________________ 2. CuCl2 ________________________ _____________________ 3. PbSO4 ________________________ _____________________ 4. Fe(NO3)3 ________________________ _____________________ 5. HgO ________________________ _____________________ II. Write the formula of the following compounds. (10 pts) 1. calcium oxide _______________ 11. diphosphorus trioxide ______________ 2. ammonium acetate _______________ 12. aluminum carbonate ______________ 3. cesium iodide _______________ 13. lithium sulfide ______________ 4. phosphoric acid _______________ 14. stannic nitrate ______________ 5. hydrobromic acid _______________ 15. mercurous phosphate ______________ 6. magnesium oxide _______________ 16. aurous oxide ______________ 7. ammonium cyanide _______________ 17. boron carbonate ______________ 8. cesium bromide _______________ 18. potassium sulfide ______________ 9. sulfuric acid _______________ 19. stannous nitrate ______________ 10. hydroiodic acid _______________ 20. mercuric phosphate ______________ 55 Chemical Reactions Symbols Meaning Yield Reversible reaction Evolution of gas Formation of precipitate Δ (s) (l) (aq) (+) (g) Steps 1. 2. 3. Heat Solid state Liquid state Aqueous solution Added to Gaseous state in writing a chemical equation Formulate a word equation. Make the skeleton equation. Balance the equation. Balancing Chemical Equations Tips; 1. Always check the equation by counting atoms on each side of the equation. For each element, the number of atoms on the left has to be equal to the number of atoms on the right. 2. Start by putting a “1” in front of the most complex compound (the one containing the greatest number and variety of atoms) 3. Balance elements that appear in multiple reactants or multiple products last. In combustion equations, this means that the oxygen is always balanced last. 4. Whole number coefficients are preferred. But use fractions during the balancing process. The equation can be scaled to remove them later. 5. Be certain that the total charge is the same on each side after you have mass-balanced equation. 6. Don’t touch the subscripts. Changing the subscripts in the formula results in an entirely different chemical compound. Remember that the coefficients show how much compound is involved in the reaction, while the subscripts show how much element is in the compound. 7. When you notice that the same polyatomic ions appear on both side of the equation, it’s much easier to balance the equation as though the polyatomic ions were ‘atoms’. 8. A missing coefficient is understood to be a ‘1’ 9. Write the equation so that the coefficients are the smallest set of integers possible. For example, if all of the coefficients are divisible by 2, divide them all by 2. Example: When silver oxide is heated, silver metal and oxygen gas are produced. 1. word equation: silver oxide silver metal + oxygen gas 2. skeleton equation: Ag2O Ag + O2 3. balanced equation: 2Ag2O 4Ag + O2 56 Types of Chemical Reactions 1. Combination or synthesis a. Metal + non-metal Mg + S b. Non-metal + non-metal C + 2H2 c. Non-metal + oxygen C + O2 d. Metal oxide + water K 2O + H 2O e. Non-metal oxide + water SO2 + H2O f. Metal oxide + non-metal oxide Na2O + SO3 ionic compound MgS covalent compound CH4 non-metal oxide CO2 metal hydroxide (base) 2KOH oxyacid H2SO4 salt Na2SO4 2. Decomposition reaction a. Hydrates yield water and anhydrous salt i. CuSO4 · 5H2O CuSO4 + 5H2O b. Chlorates when heated form metal chloride and oxygen gas i. 2KClO3 KCl + H2O c. Metal oxide when heated form the metal and oxygen gas i. 2HgO 2Hg + O2 d. Carbonates when heated yield metal oxide and carbon dioxide i. MgCO3 MgO + CO2 e. Bicarbonates when heated form metal oxide, water and carbon dioxide i. 2NaHCO3 Na2O + 2CO2 + H2O f. Electricity i. 2H2O 2H2 + O2 3. Simple/single displacement a. A + BC AC + B b. AB + C AC + B i. Mg + Zn (NO3)2 ii. Mg + LiNO3 4. Double displacement a. AB + CD i. AgNO3 + HCl Mg(NO3)2 + Zn no reaction AD + CB AgCl + HNO3 57 Activity Series of Elements Source: www.avon-chemistry.com/ch9_chart11.jpg OXIDATION – REDUCTION REACTIONS redox reactions reactions that are concerned with the transfer of electrons between and among reactants oxidation – loss of electrons reduction – gain of electrons oxidizing agent – substance that is reduced during chemical reaction; it gains electrons reducing agent – substance that is oxidized during chemical reaction; it loses electrons 58 Oxidation Number The charge that atom would carry if the compound were composed of ions Rules: 1. The oxidation number of a free and uncombined element whether monoatomic or diatomic is zero. Thus, the atoms O2, N2, Cl2 have an oxidation number of 0. 2. The oxidation number of elements belonging to group IA, IIA, and IIIA is the same as their valence. Thus, Na in NaCl has an oxidation number of +1, the oxidation number of Ba in BaO is +2 and oxidation number of Al is AlCl3 is +3. 3. The oxidation of hydrogen is +1 when it is combined with a non-metal. Hydrogen is therefore in the +1 oxidation state in CH4, NH3, H2O, and HCl. 4. The oxidation number of hydrogen is -1 when it is combined with a metal. Hydrogen is therefore in the -1 oxidation state in LiH, NaH, CaH2. 5. The oxidation number of oxygen is -2 when it is combined oxygen. Thus the oxidation number of oxygen in H2O, NaNO3 is -2. 6. The oxidation number of oxygen in peroxide is -1. Peroxides have a general formula R2O2 (for group IA) and R1O2 (for group IIA). Thus in H2O2 and CaO2 the oxidation number of oxygen is -1. 7. The sum of the oxidation number in a neutral compound is zero and equals the overall charge for an ionic species. Balancing Oxidation-Reduction Equations Methods: 1. Oxidation State Method or Valence-Change Method (http://preparatorychemistry.com/Bishop_Balancing_Redox.htm) a. Write the correct formula for all the reactants and products in the equation. HNO3 + H3AsO3 NO + H3AsO4 + H2O b. Assign the oxidation numbers to the atoms in the equation. H+N5+O32- + H3+ As3+O32- N2+O2- + c. H3+As5+O42- + H2+O2- Identify which atoms are reduced and oxidized. As +3 to +5 N +5 to +2 d. Compute the total change in oxidation number both for the reduced and oxidized atom. As Net Change = +2 N Net Change = −3 e. Make the number of electrons lost equal to the number of electrons gained by using appreciation factors. 2HNO3 + 3H3AsO3 NO + H3AsO4 + H2O f. Balance the rest of the equation by inspection. 2HNO3 + 3H3AsO3 2NO + 3H3AsO4 + H2O Balance the following reactions: Cu + HNO3 Cu(NO3)2 + NO + H2O 2. NO2 + H2 NH3 + H2O 1. 59 2. Half-reaction Method or Ion-electron Method (http://preparatorychemistry.com/Bishop_Balancing_Redox.htm) Acidic Solutions: Cr2O72−(aq) + HNO2(aq) Cr3+(aq) + NO3−(aq) a. Write the skeleton equation of the oxidation and reduction half-reactions. Cr2O7 2− Cr3+ HNO2 NO3 − b. Balance all elements except hydrogen (H) and oxygen (O). Cr2O72− 2Cr3+ HNO2 NO3 − c. Balance the oxygen atoms by adding H2O molecules on either side of the equation where O atoms are needed. Cr2O72− 2Cr3+ + 7H2O HNO2 + H2O NO3 − d. Then, balance the hydrogen atoms by adding H+ ions on either side of the equation where H atoms are needed. Cr2O72− + 14H+ 2Cr3+ + 7H2O HNO2 + H2O NO3− + 3H+ e. Balance the charge by adding electrons. 6e− + Cr2O72− + 14H+ 2Cr3+ + 7H2O HNO2 + H2O NO3− + 3H+ + 2e− f. Make the number of electrons lost in the oxidation half-reaction equal to the number of electrons gained in the reduction half-reaction. 6e− + Cr2O72− + 14H+ 2Cr3+ + 7H2O 3(HNO2 + H2O NO3− + 3H+ + 2e−) 6e− + Cr2O72− + 14H+ 2Cr3+ + 7H2O 3HNO2 + 3H2O 3NO3− + 9H+ + 6e− g. Add the 2 half-reactions algebraically. Cr2O72− + 3HNO2 + 5H+ 2Cr3+ + 3NO3− + 4H2O h. Re-check to make sure that the number of atoms and the charge balance. Basic Solutions: Cr(OH)3 + ClO3− CrO42− + Cl− a. Write the skeleton equation of the oxidation and reduction half-reactions. Cr(OH)3 CrO42− ClO3− Cl− b. Balance all elements except hydrogen (H) and oxygen (O). Cr(OH)3 CrO42− ClO3− Cl− c. Balance the oxygen atoms by adding H2O molecules on either side of the equation where O atoms are needed. Cr(OH)3 + H2O CrO42 − ClO3 Cl− + 3H2O d. Then, balance the hydrogen atoms by adding H+ ions on either side of the equation where H atoms are needed. Cr(OH)3 + H2O CrO42− + 5H+ − + ClO3 + 6H Cl− + 3H2O 60 e. Balance the charge on each side of the equation by adding electrons. Cr(OH)3 + H2O CrO42− + 5H+ + 3e ClO3− + 6H+ + 6e− Cl− + 3H2O f. Make the number of electrons lost in the oxidation half-reaction equal to the number of electrons gained in the reduction half-reaction. 2(Cr(OH)3 + H2O CrO42− + 5H+ + 3e−) ClO3− + 6H+ + 6e− Cl− + 3H2O 2Cr(OH)3 + 2H2O 2CrO42− + 10H+ + 6e ClO3− + 6H+ + 6e− Cl− + 3H2O g. Add the 2 half-reactions algebraically. 2Cr(OH)3 + ClO32CrO42− + Cl− + H2O + 4H+ − h. Add enough OH ions to each side of the equation to cancel the H+ ions. 2Cr(OH)3 + ClO3− + 4OH2CrO42− + Cl− + H2O + 4H+ + 4OH + − i. Combine the H ions and OH ions that are on the same side of the equation to form water molecule/s. 2Cr(OH)3 + ClO3− + 4OH 2CrO42− + Cl− + H2O + 4H2O j. Cancel or combine the H2O molecules. 2Cr(OH)3 + ClO3− + 4OH− 2CrO42− + Cl− + 5H2O k. Re-check to make sure that the number of atoms and the total charge on both side of the equation are balanced. 61 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 5.2 MATCHING TYPE A B C D E O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O Match Column I with Column II. Shade the circle that best corresponds to your answer (one per number). Erasures, superimpositions and alterations will invalidate correct answers. Column I Column II A. O2 + PbO B. O2 + Pb C. Pb + O 1. PbO + heat → A. NaO + H2O B. NaClO + H2 C. NaCl + H2O 2. HCl +NaOH → +Cl A. Al3O2 B. Al2O C. Al2O3 3. Al + O2 → A. H2 + ZnCl2 B. H2 + ZnCl C. H + ZnCl 4. Zn + HCl → AgCl + B. AgCl + C. AgCl2 + Ba(NO3)2 5. BaCl2 + AgNO3 A. → Ba(NO3)2 Ba2(NO3) 6. Na + H2O → 7. NaNO3 + heat → 8. Na2SO4 + BaCl2 → 9. Na2O + H2O → 10. Xhalogen + YZ → Z + YX F. Metathesis G. Analysis H. single displacement I. Synthesis J. None Balance by change-in-oxidation-number method. __ H+1 + __ Cr2O7 + __ H2S → __ Cr+3 + __ S + __ H2O Reduction: Oxidation: Balance the following reactions by ion-electron method. The following reaction occurs in acidic solution: __ ____ + __ Cr2O7-2 + __ Cl-1 → __ Cr+3 + __ Cl2 + __ ____ Reduction: Oxidation: The following reaction occurs in alkaline solution: __ ____ + __ Br2 → __ BrO3-1 + __ Br-1 + __ ____ Reduction: Oxidation: 62 Name: _________________________ Schedule: ______________________ I. Date: __________________ Rating: _________________ Activity 5.3 Indicate the oxidation number of the underlined elements in the following compounds. (10 pts) 1. Cu2O __________ 6. Hg2O __________ 2. KCl __________ 7. NaF __________ 3. HClO3 __________ 8. H3BO3 __________ 4. (PO4)-3 __________ 9. (SO4)-2 __________ 5. HBrO3 __________ 10. HNO3 __________ BALANCING AB O O O O O O AB O O O O O O AB O O O O O O O O AB O O O O O O O O AB O O O O O O O O O O O O C O O O C O O O C O O O O C O O O O C O O O O O O D E O O O O O O D E O O O O O O D E O O O O O O O O D E O O O O O O O O D E O O O O O O O O O O O O F O O O F O O O F O O O O F O O O O F O O O O O O G O O O G O O O G O O O O G O O O O G O O O O O O H O O O H O O O H O O O O H O O O O H O O O O O O Using trial-and-error method, balance the following equations. Then choose from the letters provided below and shade the circle that corresponds to your answer (one per number). Erasures and superimpositions will invalidate correct answers. A=1 D=4 G=7 J = 10 or more B=2 E=5 H=8 C=3 F=6 I=9 I J O O 1. O O 2. _1_S8 + _2_F2 → _3_SF6 O O3 I J O O4 O O5 _4_S8 + _5_O3 → _6_SO2 O O 6 I J O O 7 O O 8 _7_CaCl2 + _8_AgNO3 → _9_AgCl + _10_Ca(NO3)2 O O 9 O O 10 I J O O 11 O O 12 _11_C2H6 + _12_O2 → _13_CO2 + _14_H2O O O 13 O O 14 I J O O 15 O O 16 O O 17 _15_FeTiO3 + _16_C + _17_Cl2 → _18_FeCl3 + _19_TiCl4 + _20_CO2 O O 18 O O 19 O O 20 63 UNIT VI: Stoichiometry Atomic mass o Mass of an atom o Total mass of protons, electrons and neutrons in an atom Atomic weight/relative atomic mass o The average of the atomic masses of all the chemical element's isotopes o H = 1 g/mole o O = 16 g/mole Molecular weight (MW) o Also called formula weight o Sum of all the atomic weight of all the atoms in a molecule o NaCl: Na: 1 x 23 = 23 g/mole Cl: 1 x 35 = 35 g/mole 58 g/mole MOLE Refers to the measure of the amount of particles in matter Called the “chemist’s dozen” SI unit for the amount of substance 1 mole of particles = 6.02 x 1023 particles (Avogadro’s number) o 1 mole of O = 6.02 x 1023 atoms o 1 mole of NaCl = 6.02 x 1023 molecules number of atoms Avogadro' s Number Number Of Molecules Number of moles = Avogadro' s Number Weight In Grams Of A Subs tan ce Number of moles = Molecular Weight Of A Subs tan ce Number of moles = Sample Problems: 1. How many moles are 3.40 x 1024 atoms of oxygen? No. of moles = number of atoms Avogadro' s Number = 3.40 x 1024 atoms 6.02 x 1023 atoms/mole No. of moles = 5.65 moles of O 2. How many moles are 6.71 x 1026 molecules of salt? No. of moles = Number Of Molecules Avogadro' s Number No. of moles = 6.71 x 1026 molecules 6.02 x 1023 molecules/mole No. of moles = 1.11 x 103 moles NaCl 64 3. Calculate the number of moles in 65 grams of H 2O? No. of moles = Weight In Grams Of A Subs tan ce Molecular Weight Of A Subs tan ce MWH2O : H O 2 x 1 g/mole = 2 g/mole 1 x 16 g/mole = 16 g/mole 18 g/mole No. of moles = 65 grams 18 g/mole No. of moles = 3.61 moles of H2O Percentage Composition This is the relative measure of the mass of each element found in the compound % mass of element = Mass In Grams Of Element x 100 Mass In Grams Of Compound Sample Problems: 1. Compute for the percentage composition of the compound formed from the reaction of 45 grams of Na and 34 grams of Cl. Mass of the Compound = 45 grams Na + 34 grams Cl Mass of the Compound = 79 grams Na = 45 grams x 100 79 grams Cl = = 56.96% 34 grams x 100 79 grams = 43.04% 2. Calculate the percentage composition of potassium permanganate. Potassium permanganate = KMnO4 MW of KMNO4 : K 1 x 39 39 Mn 1 x 55 55 O 4 x 16 64 158 g/mole K= 39 grams / mole x 100 158 grams / mole = 24.68% Mn = 55 grams / mole x 100 158 grams / mole = 34.81% O= 64 grams / mole 158 grams / mole = 40.51% 65 Empirical Formula Gives the lowest whole number ratio of elements in a compound Example: benzene (C6H6) has a ratio of 6:6 or 1:1; therefore the empirical formula is CH Sample Problems: 1. Find the empirical formula of a compound that is 48.38% carbon, 8.12% hydrogen, and 43.5% oxygen by mass. a. Get the mass of each element by assuming a certain overall mass for the sample (100 g). C = 48.38% = 48.38 g H = 8.12% = 8.12 g O = 43.50% = 43.50 g 100.00 g b. Convert the mass of each element to moles of each element using their atomic masses. C = (48.38 g) (1 mol/12 g) = 4.03 mol C H = (8.12 g) (1 mol/1 g) = 8.12 mol H O = (43.50 g) (1 mol/16 g) = 2.72 mol O c. Find the ratio of each element by dividing the number of moles of each by the smallest number of moles. C = (4.03/2.72) = 1.48 ≈ 1.50 H = (8.12/2.72) = 2.99 ≈ 3 O = (2.72 /2.72) = 1 d. Use the mole ratio to write the empirical formula. (because not all the answers are whole numbers, multiply the ratios by a number to make them whole). C = 1.50 mol x 2 = 3 H = 3 mol x 2 = 6 O = 1 mol x 2 = 2 Empirical Formula: C3H6O2 2. Calculate the empirical formula of a compound composed of 4.5 g of carbon and 1.5 g of hydrogen. a. Compute for the number of moles using the atomic mass of each element. C = (4.5 g) (1 mol/12g) = .0375 mol C H = (1.5 g) (1 mol/1g) = 1.5 mol H b. Find the ratio of each element by dividing the number of moles of each by the smallest number of moles. C = (0.375/.0375) = 1 H = (1.5/0.375) = 4 c. Use the mole ratio to write the empirical formula. Empirical formula = CH4 66 Molecular Formula Gives the actual formula of a compound Could either be the same as the empirical formula or be a whole-number multiple of the empirical formula Example: C6H6 is the molecular formula of the empirical formula CH Sample Problems: 1. The empirical formula for vitamin C is C3H4O3. Based from an experimental data, the molecular mass of vitamin C is about 180 g/mole. What is the molecular formula of vitamin C? a. Divide the molecular weight by the empirical formula weight to find a multiple or factor. Molecular weight = 180 g/mole EF weight of C3H4O3 = (3 x 12 g/mole) + (4 x 1 g/mole) + (3 x 16 g/mole) = 88 g/mole Factor/Multiple = Molecular Weight Empirical Formula Weight Factor/Multiple = 180 g/mole 88 g/mole Factor/Multiple = 2 b. Multiply the subscript of the empirical formula with the factor or multiple. (C3H4O3)2 = C3x2 H4x2 O3x2 MF: C6H8O6 2. A compound is composed of 40.00% C, 6.72% H, and 53.29% O; and has a molecular weight of 180 g/mol. Compute its molecular formula. a. Find the empirical formula of the compound. C = 40.00% = 40.00 g H = 6.72% = 6.72 g O = 53.28% = 53.28 g 100.00 g C = (40.00 g) (1 mol/12 g) = 3.33 mol C H = (6.72 g) (1 mol/1 g) = 6.72 mol H O = (53.28 g) (1 mol/16 g) = 3.33 mol O C = (3.33/3.33) = 1 H = (6.72/3.33) = 2 O = (3.33 /3.33) = 1 EF: CH2O b. Divide the molecular weight by the empirical formula weight to find a multiple or factor. Molecular weight = 180 g/mole EF weight of CH2O = 12 g/mole + 2 g/mole + 16 g/mole = 30 g/mole Factor/Multiple = c. Molecular Weight Empirical Formula Weight Factor/Multiple = 180 g/mole 30 g/mole Factor/Multiple = 6 Multiply the subscript of the empirical formula with the factor or multiple. (CH2O)6 = C1x6 H2x6 O1x6 MF: C6H12O6 67 Stoichiometry the quantitative description of the relationships between reactants and between reactants and products in a chemical reaction 1. Mole to Mole Relationship How many moles of NH3 could be produced if 4 moles of N2 were reacted with Hydrogen? a. Write the balanced equation. N2 + 3 H2 ---> 2 NH3 b. Determine the mole relationship between the given component and the required component. Relative moles (from the equation): 1 mole N2 = 2 moles NH3 Given moles (from the problem): 4 moles N2 = X moles NH3 c. Form the proportion of the given and required components. Then solve for the unknown. Given mole N2 = Given mole NH3 Rel. mole N2 Rel. mole NH3 4 moles N2 = 1 mole N2 X = 8 moles NH3 X moles NH3 2 moles NH3 2. Mole to Mass Relationship From the equation: N2 + 3 H2 ---> 2 NH3, determine the mass in grams of H2 that will react with the 4 moles of N2. a. Write the balanced equation N2 + 3 H2 ---> 2 NH3 b. Convert the moles of the given component to moles of the requested component. Relative moles (from the equation): 1 mole N2 = 3 moles H2 Given moles (from the problem): 4 moles N2 = X moles H2 Given mole N2 = Given mole NH3 Rel. mole N2 Rel. mole NH3 4 moles N2 = 1 mole N2 X = 12 moles H2 c. X moles H2 3 moles H2 Convert the moles of the requested component to mass in grams. MW H2: 2 x 1 g/mole = 2 g/mole H2 12 moles H2 x 2 g H2 = 24 grams H2 1 mole H2 3. Mole to Volume Relationship How many liters of NH3 can be produced at 27 °C and 760 torr if 20 moles of N2 are utilized? (Use the equation: N2 + 3 H2 ---> 2 NH3) a. Convert the moles of the given component to the moles of the requested component using the coefficients of the balanced equation. 1 mole N2 = 2 moles NH3 20 moles N2 x 2 moles NH3 = 40 moles NH3 1 mole N2 68 b. Convert the moles of the requested component to its volume using the Ideal Gas Law Equation. PV = nRT T = 27 + 273 = 300 K P = 760 torr x 1 atm = 1 atm 760 torr V= nRT P = (40 moles) (0.0821 L-atm/mol-K) (300 K) = 985.20 L NH3 1 atm 4. Mass to Mass Relationship From the equation: N2 + 3 H2 ---> 2 NH3, compute the grams of NH3 that will be produced if 10 grams of H2 reacted with N2. a. Balance the equation. N2 + 3 H2 ---> 2 NH3 b. Compute for the moles of the given component using its mass. MW H2: 2 x 1 g/mole = 2 g/mole H2 10 g H2 x 1 mol H2 = 5 moles H2 2 g H2 c. Convert the moles of the given component to moles of the requested component using the coefficients of the balanced equation. 3 moles H2 = 2 moles NH3 5 moles H2 x 2 moles NH3 = 3.33 moles NH3 3 moles H2 d. Convert moles of the requested component to its mass. MW NH3: N = 1 x 14 = 14 g/mole H=3x1 = 3 g/mole 17 g/mole 3.33 moles NH3 x 17 grams NH3 = 56.61 grams NH3 1 mole NH3 5. Mass to Volume Relationship How many liters of H2 will be required at 300 K and 3 atm to cosume 56 grams of N 2? (Use the reaction: N2 + 3 H2 ---> 2 NH3) a. Balance the equation. N2 + 3 H2 ---> 2 NH3 b. Compute the moles of the given component using its mass. MW N2: 2 x 14 g/mole = 28 g/mole N2 56 g N2 x 1 mol N2 = 2 moles N2 28 g N2 69 c. Convert the moles of the given component to moles of the requested component using the balanced equation. 1 moles N2 = 3 moles H2 2 moles N2 x 3 moles H2 = 6 moles H2 1 mole N2 d. Convert moles of the requested component to its volume using the Ideal Gas Law Equation. PV = nRT V= nRT P = (6 moles H2) (0.0821 L-atm/mol-K) (300 K) = 49.26 L H2 3 atm 6. Volume to Volume Relationship What is the volume of NH3 that will be produced if 10 liter of N2 are used? (Use the reaction: N2 + 3 H2 ---> 2 NH3) a. Balance the equation. N2 + 3 H2 ---> 2 NH3 b. Convert the volume of the given component to liters of the required component using the coefficients of the balanced equation. 1 liter N2 = 2 liters NH3 10 liters N2 x 2 liters NH3 = 20 liters NH3 1 liter N2 7. Theoretical and Actual Yield Theoretical yield maximum amount of product that could be computed given the amounts of the reactants. Actual yield amount of product produced when the reaction is carried out in the laboratory Percent Yield = Acutal Yield x 100 Theoretical Yield Example: 1. What is the percent yield for a reaction if you predict the formation of 21 grams of C6H12 and actually recovered only 3.8 grams? Percent Yield = Acutal Yield x 100 Theoretical Yield = 3.8 grams x 100 21 grams Percent Yield = 18.10% 70 2. When 10 grams of methane in an excess of oxygen is burned, 19.8 grams of water is produced. What is the percent yield of water? a. Balance the equation. CH4 + 2O2 -> CO2 + 2H2O b. Convert the mass of the given component to moles using the balanced equation. MWCH4: C = 1 x 12 g/mole = 12 g/mole H = 4 x 1 g/mole = 4 g/mole 16 g/mole 10 grams CH4 x 1 mole CH4 = 0.625 mole CH4 16 g CH4 c. Form the proportion of the given and required components. Then solve for the unknown. 1 mole CH4 = 2 moles H2O 0.625 mole CH4 = 1 mole CH4 X = 1.25 moles H2O X moles H2O 2 moles H2O d. Convert the computed number of moles to mass of the required component to get the theoretical yield. MW H2O: H = 2 x 1 g/mole = 2 g/mole O = 1 x 16 g/mole = 16 g/mole 18 g/mole 1.25 moles H2O x 18 g H2O = 22.5 grams H2O 1 mole H2O e. Solve for the percent yield. Percent Yield = Acutal Yield x 100 Theoretical Yield = 19.8 g x 100 22.5 g Percent Yield = 88 % 71 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 6.1 Compute for the unknown. Show all solutions. ___________________11. How many moles are there in 50 g CCl4 ? ___________________12. How many molecules are there in 25 g H2SO4? ___________________13. How many moles are there in 1.269 X 1024 molecules of NaNO3? ___________________14. What is the mass, in grams, of 0.75 mol Ca3(PO4)2 ? ___________________15. What is the mass, in grams, of 1.35 X 1023 molecules C6H12O6 ? ___________________16. How many particles are there in 1.38 mol CuSO4 · NH4NO3 · 12 H2O ? III. Identify / Solve the following items in this hydrate, FeSO4 · 6 H2O. (Show derivation of % composition of each component at the back of this sheet.) Components No. of Atoms Atomic Mass Relative Mass % Composition % composition of O = ___________ Solution: 72 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 6.2 Compute for the unknown. Show all solutions. 1. The MW of cholesterol is 386.73 g/mol and the compound contains 83.9 % C, 12.0 % H and the remaining is oxygen. ___________________a. Compute for the mole ratio of C. ___________________b. Compute for the mole ratio of H. ___________________c. Compute for the mole ratio of O. ___________________d. What is the empirical formula of the compound? ___________________e. What is the molecular formula of the compound? 2. When 6.65 g of the hydrate NiSO4 · XH2O was heated in a vacuum, the water was driven off and 3.67 g of anhydrous NiSO4 remained. ___________________a. Calculate the number of moles of NiSO4. ___________________b. Calculate the number of moles of H2O. ___________________c. What is the empirical formula ( the value of X) ? 3. In a convenient laboratory preparation of pure nitrogen gas, NaN3 decomposes to Na and N2 upon heating. ___________________a. Write a balanced equation. ___________________b. What number of moles of NaN3 is required to prepare 1.00 mol of N2 ? ___________________c. What mass of N2 is produced by the decomposition of 2.5 g of NaN3 ? ___________________d. What volume of Na is produced when 11.75 li of N2 is prepared ? 73 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 6.3 1. The acid secreted by the cells of the stomach lining is a hydrochloric acid solution that typically contains 0.282 g of HCl per 50.00mL of solution. What is the concentration of this acid? 2. A sample of tin having a mass of 3.996 grams was oxidized and found to have combined with 1.077 grams of oxygen. Calculate the empirical formula of this oxide of tin. 3. Dibutyl succinate is an insect repellant used against household ants and roaches. Its composition is 62.58% C, 9.63% H and 27.79% O. Its composition experimentally determined molecular mass is 230amu. What are the empirical and molecular formulas of dibutyl succinate? 4. Fructose is a very sweet naturally occurring sugar present in honey, fruits, and fruit juices. It has a molar mass of 180.1 g/mol and a composition of 40.0% C, 6.7% H, and 53.3% O. Calculate the molecular formula of fructose. 5. Calculate the number of moles corresponding to: a. 0.10g of the secondary extracellular cation, Ca++ b. 4.0g of the major intracellular cation, K+ 6. Isopropyl alcohol, commonly known as rubbing alcohol, is used as an antiseptic. It is composed of C, H, and O. Combustion of isopropyl alcohol produces 0.561g CO 2 and 0.306 g H2O. Determine the empirical formula of isopropyl alcohol. 74 UNIT VII: Solutions Solution A homogenous mixture of two or more substances in which settling does not occur A homogenous mixture in which one substance is dissolved in another substance o Solvent – the substance that does the dissolving o Solute – the substance that is dissolved Types of Solutions Type Solvent Solute Example Gas Gas Air Gas Liquid Moist air Gas Solid Soot in air Liquid Liquid Solid Brine, syrup Liquid Liquid Alcohol in water, vinegar Liquid Gas Carbonated beverages Solid Solid Solid Copper in nickel, brass, steel Solid Liquid Mercury in water Solid Gas Hydrogen dissolved in platinum metal Source: Interactive Chemistry by Aurora Franco, et. al. 2000: 208) Gaseous The Solution Process The solute particles are separated from the surface of the solid solute. Dissolving is aided by the attraction between the solute and the solvent molecules. This needs heat or energy (endothermic) Solvent particles are moved apart to allow solute molecules to enter the liquid. This needs energy (endothermic). The solute molecules are attracted to solvent molecules. This gives up energy (exothermic). Rate of Solution agitating or stirring the solution heating the solute powdering the solid solute Solubility measures of how much of that solute can be dissolved in a given amount of solvent under certain conditions Factors affecting the solubility of substance: Nature of solute and solvent Non-polar solvents – benzene and CCl4 Polar solvents - water Effect of Temperature Effect of Pressure 75 Concentration of Solution Refers to the amount of solute dissolved in a certain amount of solvent Concentrated solution – much of solute is dissolved in a solvent saturated solution o solution that has dissolved the maximum amount of solute for a given amount of solvent at a given temperature unsaturated solution o solution that contains less solute than it can hold at a certain temperature and pressure supersaturated solution o solution that can hold more solute than that which is normal for that temperature Expressing Concentrations 1. Percent by mass mass mass of of solute x 100% solution % by mass = a. A bottle of a certain ceramics tile cleanser which is a solution of hydrogen chloride, contains 130 g HCl and 750 g of H2O. What is the % by mass of HCl in this cleanser? Given: mass of solute = 130 g HCl Mass of solvent = 750 g H2O Required: % by mass of HCl Answer: 14.77 % b. A sample of 0.892 g of potassium chloride is dissolved in 54.6 g of water. What is the percent by mass of KCl in this solution? 2. Percent by volume volume volume of of solute x 100% solution % by volume = a. What is the percent by volume of ethanol in the final solution when 75 mL of ethanol is diluted to a volume of 250 mL of water? Given: volume of solute = 75 mL ethanol Mass of solvent = 250 mL H2O Required: % by volume of ethanol Answer: 23.08 % b. What is the percent by volume of acetic acid in a fiscal volume when 75 mL of acetic acid is diluted to a volume of 250 mL of water? 76 3. Molarity (M) moles of solute liter of solution mass of solute Molarity (M) = MWsolute X Vsolution Molarity (M) = a. Calculate the molar concentration of a solution that contains 15 g of KOH in 225 mL of solution. Given: mass of solute = 15 g KOH Volume of solution = 225 mL (0.225 L) MW of KOH = 56 g/mole Number of moles = 0.27 moles KOH Answer: 1.19 M b. Calculate the molarity of the solution containing 10 grams of sulfuric acid in 500 mL of solution. Given: mass of solute = 10 g H2SO4 Volume of solution = 500 mL (0.500 L) MW of H2SO4 = 98 g/mole Answer: 0.204 M 4. Molality (m) moles ki log ram mass Molality = MWsolute of of of X solute solvent solute Ksolvent Molality = a. 2.3 grams of ethanol is added to 500 grams of water. Determine the molality of the resulting solution. Given: mass of solute = 2.3 grams Mass of solvent = 500 grams (0.5 kg) MW of solute = 46 g/mole Required: molality of the solution Answer: 0.1 molal b. Determine the mass of water to which 293 grams of NaCl is added to obtain a 0.25 molal solution. Given: mass of solute = 293 grams Molality of the solution = 0.25 molal Required: mass of water Answer: 20 kg of water 77 5. Normality (N) mass Eq of solute x Lsolution MW of solute Equivalent weight = Factor(F ) Eq N = molarity x mole N= a. F for Acid is the number of replaceable hydrogen ion HCl ; F = 1 H2SO4 ; F = 2 b. F for Base is the number of replaceable hydroxyl ion NaOH; F = 1 Ba (OH)2; F = 2 c. F for Salt is the valence of the positive ion NaNO3; F = 1 K2CO3; F = 2 **Calculate the normality of a solution containing 2.45 grams of H 2SO4 in 2 liters of solution? Given: mass of H2SO4 = 2.45 grams Volume of solution = 2 liters MW of the solution = 98 g/mol Required: Normality of the solution Solution: Equivalent weight of H2SO4 = (98/2) = 49 g/mol N = [2.45/(49 x 2)] = 0.025 normal **How many grams of sulfuric acid are contained in 3 liters of 0.500 N solution? Given: Volume of solution = 2 liters MW of the solution = 98 g/mol N = 0.500 normal Required: mass of solute Solution: Equivalent weight of H2SO4 = (98/2) = 49 g/mol Mass of solute = (0.5 x 49 x 3)] = 73.5 g 78 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 7.1 A Ca(OH)2 solution has a density of 0.55 g/ml and weighs 50 g. It is prepared from 23 grams of Ca(OH)2. Solve for: ____________________a. molarity ____________________b. normality ____________________c. molality ____________________d. mole fraction of solute ____________________e. mole fraction of solvent ____________________f. % by volume of solvent if the volume and weight of the solvent are equal in value 5. If the solute weighs 183.72 g, what volume, in liters, of the following compounds should be used to prepare: ____________________a. 12.65 M of NaOH ____________________b. 9.05 N of KMnO40 → KMnO4-2 79 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 7.2 1. Sam is a nursing student. He has been asked to intravenously inject his patient with 10cc of an isotonic preparation. Mistakenly, he injected his patient with pure water. What is likely to happen to the red blood cells near the site of injection? 2. Anne is Sam’s patient. She was carefully watching him fill an IV bottle with a mixture specially ordered by the physician. She noticed that he accidentally filled the bottle with concentrated (10%) NaCl solution instead of the mixture from the pharmacy. Why should she refuse to allow Sam to attach the IV bottle to her system? 3. Sam is now assigned to the surgical unit. He is given a piece of a living tissue and asked to put it in a fluid before taking the sample to the pathology laboratory. What essential characteristics must such fluid have in order not to damage the tissue? 80 pH The rough measure of the acidity of a solution. The p stands for “potenz” which means the potential to be and the H stands for Hydrogen. Denotes negative logarithm of the hydrogen ion concentration. is divided into fourteen units 7 is neutral Basic solution has a ph> 7 Acidic solution has pH < 7 0 1 2 3 4 more acidic 5 6 7 8 neutral 9 10 11 12 13 14 more basic pH = - log [H+] pOH = - log [OH-] Kw = 1.0 x 10-14 = [H+][OH-] If we take the negative logarithm of both sides of the equilibrium expression, it becomes, -log Kw = -log ([H+][OH-]) -log Kw = -log [H+] + –log [OH-] -log 1.0 x 10-14 = -log [H+] + – log [OH-] 14 = pH + pOH ***The autoionization of water H 2O + H 2O H3O + OH *** Kw (equilibrium constant) Known as the ion product for water Pure water at 25 °C (H3O+ = OH- = 1.0 x 10-7 mol/L) Calculation of pH 1. Calculate the pH of a solution in which the H+ concentration is 0.070 mol/L. a. [H+] = 0.070 M = 7.0 x 10-2 M b. pH = -log [H+] = -log [7.0 x 10-2] = 1.15 2. Compute for the pH of a solution that contains 3.65 g of HCl in 2.00 L of solution. a. Molarity = number of moles of solute number of liters of solution 1molHCl ? molHCl 3.65 gHCl = x = 0.0500 mol HCl/L or 0.0500 M Lsolution 2.00 Lsolution 36.5 gHCl b. [H+] = 0.0500 M = 5.0 x 10 -2 M c. pH = -log [H+] = -log [5.0 x 10-2] = 1.30 3. The pH of a solution if 3.301. What is the concentration of H+ in this solution? a. pH = -log [H+] b. 3.301 = -log [H+] c. -3.301 = log [H+] d. antilog -3.301 = H+ e. H+ = 5.00 x 10-4 M 81 Calculation of pOH 1. Calculate [H+], pH, [OH-1], and pOH for a 0.015 M HNO3 solution. a. [H+] = 0.015 M (because it is an acid) b. pH = - log [H+] = -log [0.015] = 1.82 c. pH + pOH = 14.00 d. pOH = 14.00 – pH = 14.00 – 1.82 = 12.18 e. [H+] [OH-] = 1.0 x 10-14 f. [OH-] = (1.0 x 10-14) ÷ [H+] = (1.0 x 10-14) ÷ 0.015 = 6.7 x 10-13 M 2. Calculate [H+], pH, [OH-1], and pOH for a 0.015 M Ca(OH)2 solution. a. [OH-] = 2 x 0.015 M = 0.030 M b. pOH = -log [OH-] = -log (0.030) = 1.52 c. pH + pOH = 14.00 d. pH = 14.00 – pOH = 14.00 – 1.52 = 12.48 e. [H+] [OH-] = 1.0 x 10-14 f. [H+] = (1.0 x 10-14) ÷ [OH-] = (1.0 x 10-14) ÷ 0.030 = 3.3 x 10-13 M 82 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 7.3 A. Solve for the H+, OH-, pH, and pOH values. (20 pts) H+ Solution a. 0.045 M LiOH OH- pH pOH b. 0.185 M HBr c. 0.230 M Mg(OH)2 d. 0.0099 M HI e. 2.30 x 10 -4 M HF B. Calculate the following values for each solution. (24 pts) H+ OH- pH 2.36 pOH 11.32 10.78 7.21 3.58 4.97 12.43 4.65 C. The normal pH of Human Blood ranges from 7.35 to 7.45. Calculate the concentrations of H3O+ and OH- ions in human blood that has a pH of 7.45. 83 Colligative Properties of Solutions are properties that depend upon the concentration or number of solute molecules or ions, but not upon the identity of the solute 1. vapor pressure lowering 2. boiling point elevation 3. freezing point depression 4. osmotic pressure Vapor Pressure the pressure of the vapor resulting from evaporation above a sample in a closed container the rate of condensation of the gas becomes equal to the rate of evaporation of the liquid or solid Raoult’s Law o The vapor pressure of a volatile or of an ideal solution is dependent on the vapor pressure of each component and the mole faction of the component present in the solution. o Vapor Pressure of Solution = (Mole Fraction of solvent) (Vapor Pressure of Pure Solvent) o Mole Fraction of a solvent = number of moles of solvent total number of moles of solution and of solvent Example: Determine the vapor pressure of a solution at 25 °C that has 45 grams of glucose dissolved in 72 grams of water. The vapor pressure of pure water at 25 °C is 23.8 torr. a. Compute the number of moles of the substance/solute by using its mass. MWglucose: C = 6 x 12 = 72 g/mole H = 12 x 1 = 12 g/mole O = 6 x 16 = 96 g/mole 180 g/mole 45 grams x 1mole C6H12O6 = 0.25 mole 180 grams C6H12O6 b. Compute the number of moles of the solvent by using its mass. MWH2O: 18 g/mole 72 grams x 1 mole H2O = 4 moles 18 grams H2O c. Determine the mole fraction of the solute Mole fraction of solvent= number of moles of solvent total number of moles of solution and of solvent = ________4 moles H2O 0.25 moles C6H12O6 + 4 moles H2O Mole fraction of solvent = 0.94 d. Determine the vapor pressure of the solution Vapor Pressure of Solution = (Mole Fraction of solvent) (Vapor Pressure of Pure Solvent) = (0.94) (23.8 torr) V.P. of Solution = 22.38 torr 84 Freezing Point Depression Change that occurs in the temperature at which a liquid freezes when a solute is dissolved in it The solution has a lower freezing point than a pure solvent Freezing point depression o ΔTf = Kfm where ΔTf = freezing point depression Kf = molal freezing point constant of the solvent m = molal concentration o Freezing point of solution = FPsolvent - ΔTf Example: Compute the freezing point of a solution of 90 grams of glucose dissolved in 750 grams of water. The K f of water is -1.86 °C/m. The freezing point of pure water is 0 °C. a. Compute the number of moles of the substance/solute by using its mass. MWglucose: C = 6 x 12 = 72 g/mole H = 12 x 1 = 12 g/mole O = 6 x 16 = 96 g/mole 180 g/mole 90 grams x 1mole C6H12O6 = 0.5 mole 180 grams C6H12O6 b. Convert the mass of solvent to kilograms. 750 grams H2O x 1 kg H2O = 0.75 kg H2O 1000 g H2O c. Calculate the molal concentration. m = moles of solute kilogram of solvent = 0.5 mole C6H12O6 0.75 kg H2O m = 0.67 m d. Compute the freezing point of solution. ΔTf = Kfm = (-1.86 °C/m) (0.67 m) ΔTf = -1.25 °C Freezing point of solution = FPsolvent - ΔTf = 0 °C – (-1.25 °C) Freezing point of solution = 1.25 °C Boiling Point Elevation Change that occurs in the temperature at which a liquid boils when a solute is dissolved in it The solution has a higher boiling point than a pure solvent Boiling Point Elevation o ΔTb = Kbm where ΔTb = boiling point elevation Kb = molal boiling point constant of the solvent m = molal concentration o Boiling point of solution = BPsolvent + ΔTb 85 Example: The normal boiling point of benzene is 80.1 oC. It has a boiling point elevation constant of 2.53 oC/m. If we make up a 0.5 molal solution of Br2 in benzene, what is the boiling point of the mixture? ΔTb = Kbm = (2.53 °C/m) (0.5 m) ΔTb = 1.27 °C Boiling point of solution = BPsolvent + ΔTb = 80.1 °C + 1.27 °C Boiling point of solution = 81.37 °C Osmotic Pressure Osmosis is the diffusion of small particles through a semi-permeable membrane Osmotic pressure is a hydrostatic pressure produced by the difference of solute concentration on the opposite sides of the semi-permeable membrane π = MRT where: π = osmotic pressure M = molarity of the solution R = gas constant (0.08205 L-atm/mole-K) T = temperature in Kelvin Example: What is the osmotic pressure of a sugar solution that contains 100 grams of sucrose C 12H22O11 which is dissolved in water to make 1 liter of solution at 25 °C? a. Compute the number of moles of the substance/solute by using its mass. MWsucrose: C = 12 x 12 = 144 g/mole H = 22 x 1 = 22 g/mole O = 11 x 16 = 176 g/mole 342 g/mole 100 grams x 1mole C12H22O11 342 grams C12H22O11 = 0.29 mole b. Determine the molarity concentration. Molarity = moles of solute Liters of solution = 0.29 mole C12H22O11 1 L solution Molarity = 0.29 M c. Calculate the osmotic pressure. T = 25 + 273 = 298 K π = MRT = (0.29) (0.08205 L-atm/mole-K) (298 K) π = 7.09 atm 86 Name: _________________________ Schedule: ______________________ Date: __________________ Rating: _________________ Activity 7.4 1. What is the osmotic pressure at 25 °C of an aqueous solution that is 0.0010 M C12H22O11 (Sucrose)? 2. What mass of urea [CO (NH2)2] would you dissolve in 225 mL of solution to obtain an osmotic pressure of 0.015 atm at 25 °C? 3. What is the a) Molality, b) Freezing point, and c) Boiling point of a solution containing 2.68 g of Naphthalene (C10H8) in 18.4 of Benzene (C6H6)? 4. The freezing point of a solution of 8.00 g of an unknown compound dissolved in 60.0 g of acetic acid if 13.2 0C. Calculate the molar mass of the compound. 5. A solution is prepared by dissolving 6.85 g of ordinary sugar (sucrose, C12H22O11, 34 g/mol) in 34.0 g of water. Calculate the boiling point of the solution. 6. Sucrose is a non volatile, non-ionizing solute in water. Determine the vapour pressure lowering at 25 °C, of the 1.25 molal sucrose solution. Assume that the solution behaves ideally. The vapour pressure of pure water at 25 °C is 23.8 torr. 7. Calculate the (a) lowering of the vapour pressure and (b) the vapour pressure of a solution prepared by dissolving 25.5 g of Naphthalene, C 10H8 ( a non-volatile electrolyte) in 150.0 g of Benzene C6H6 at 20 °C. Assume that the solution is ideal. The vapour pressure of pure benzene is 74.6 torr at 20 °C. 87