CHAPTER 1 The Foundations of Chemistry What is Chemistry? Physical science that studies the composition, structure, and properties of matter and the changes it undergoes Includes many different branches of study (focuses on a particular area, they do overlap) Organic Inorganic Physical Analytical Biochemistry Theoretical Chemistry is…… A natural science A language with its own vocabulary A way of thinking Chapter 1 Chemistry Click below to watch the Visual Concept. Visual Concept Scientific Method Observations Theory (Model) Hypothesis Modify Experiment Prediction Law Experiment What is Matter? Matter is anything that takes up space and has mass Mass is the amount of matter in an object Mass is resistance to change in motion along a smooth and level surface Matter Atoms are the building blocks of all matter An atom is the smallest particle of an element that maintains its chemical identity through all chemical and physical changes. 7 Properties of Matter Physical propertiescharacteristic that can be observed without changing the identity Observed with the senses Changes of state Density, color solubility Chemical propertiesindicates how a substance reacts with something else When observed original substance is changed Rusting or oxidation Chemical Rxn Properties of Matter Chapter 1 Comparing Physical and Chemical Properties Click below to watch the Visual Concept. Visual Concept Characteristic Properties Quality of a substance that never changes, used to identify substance Extensive- depends on amount of matter present Mass volume Intensive- does not depend on amount of matter present Melting point Boiling point Chapter 1 Comparing Extensive and Intensive Properties Click below to watch the Visual Concept. Visual Concept Changes in Matter Physical changealter form of a substance but NOT identity Original substance continues to exist Chemical changesubstances combine/break apart to form new substance Original substance no longer exists Chemical Changes, continued • A change in which one or more substances are converted into different substances is called a chemical change or chemical reaction. • The reactants are the substances that react in a chemical change. • The products are the substances that are formed by the chemical change. carbon + oxygen reactants carbon dioxide product Carbon plus oxygen yields (or forms) carbon dioxide. Chapter 1 Evidence of a Chemical Change Chapter 1 Chemical Reaction Click below to watch the Visual Concept. Visual Concept Chapter 1 Comparing Chemical and Physical Changes Click below to watch the Visual Concept. Visual Concept Physical vs. Chemical Examples: rusting iron chemical dissolving in water physical burning a log chemical melting ice physical grinding spices physical Mixtures, Substances, Compounds, & Elements Substance matter in which all samples have identical composition and properties Elements substances that cannot be decomposed into simpler substances via chemical reactions Elemental symbols found on periodic table 20 Chapter 1 Element Click below to watch the Visual Concept. Visual Concept Mixtures, Substances, Compounds, & Elements Mixtures composed of two or more substances can be separated by physical means homogeneous mixtures heterogeneous mixtures Compounds substances composed of two or more elements in a definite ratio by mass can be decomposed into the constituent elements by chemical means Water is a compound that can be decomposed into 22 simpler substances – hydrogen and oxygen Chapter 1 Compounds Click below to watch the Visual Concept. Visual Concept Chapter 1 Classification Scheme for Matter Click below to watch the Visual Concept. Visual Concept States of Matter Solids Particles packed tightly together Have definite volume and definite shape Particles vibrate Gases Change volume very easily Particles spread apart, filling all space available to them No definite shape nor volume Liquids No shape of its own, takes shape of its container Has definite volume States of Matter © 2009, Prentice-Hall, Inc. Chapter 1 Section 2 Matter and Its Properties Liquid Click below to watch the Visual Concept. Visual Concept States of Matter Changes in state require changes in energy. heating cooling 28 States of Matter Definite Definite Temp. Volume? Shape? increase Solid Liquid Gas YES YES NO Compressible? YES Small Expans. NO NO Small Expans. NO NO Large Expans. YES A Molecular View Dalton’s Atomic Theory Dalton’s atomic theory summarized the nature of matter as known in 1808 1) 2) 3) 4) 5) An element is composed of extremely small indivisible particles called atoms. All atoms of a given element have identical properties, which 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 each other in small wholenumber ratios. The relative numbers and kinds of atoms are constant in a given compound. 30 Natural Laws Scientific (natural) law A general statement based the observed behavior of matter to which no exceptions are known. Law of Conservation of Mass Law of Conservation of Energy Law of Conservation of Mass and Energy Einstein’s Theory of Relativity E=mc2 31 Number vs. Quantity Quantity = number + unit UNITS MATTER!! Measurements in Chemistry Quantity length mass time current temperature amt. substance Unit meter kilogram second ampere Kelvin mole Symbol m kg s A K mol 33 Measurements in Chemistry Metric Prefixes Prefix mega- Symbol M Factor 106 kilo- k 103 BASE UNIT --- 100 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12 Units of Measurement Definitions Mass measure of the quantity of matter in a body Weight measure of the gravitational attraction for a body 35 Units of Measurement Common Conversion Factors Length 1 m = 39.37 inches 2.54 cm = 1 inch Volume 1 liter = 1.06 qt 1 qt = 0.946 liter See Table 1-8 for more conversion factors 36 Use of Numbers Exact numbers 1 dozen = 12 things Accuracy how closely measured values agree with the correct value Precision how closely individual measurements agree with each other 37 Accuracy and Precision Click below to watch the Visual Concept. Visual Concept Significant Figures Indicate precision of a measurement. Consists of all the digits known with certainty plus one final digit, which is somewhat uncertain or estimated 2.35 cm Significant Figures Rules Counting Sig Figs Count all numbers EXCEPT: Leading zeros -- 0.0025 Trailing zeros without a decimal point -- 2,500 Calculating with Significant Figures Exact Numbers do not limit the # of sig figs in the answer. Counting numbers: 12 students Exact conversions: 1 m = 100 cm “1” in any conversion: 1 in = 2.54 cm Significant Figures, continued Rounding Counting Sig Fig Examples 1. 23.50 4 sig figs 2. 402 3 sig figs 3. 5,280 3 sig figs 4. 0.080 2 sig figs Calculating with Significant Figures Multiply/Divide - The # with the fewest sig figs determines the # of sig figs in the answer. (13.91g/cm3)(23.3cm3) = 324.103g 4 SF 3 SF 3 SF 324 g Calculating with Significant Figures Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer. 3.75 mL + 4.1 mL 7.85 mL 7.9 mL 224 g + 130 g 354 g 350 g Practice Problems (15.30 g) ÷ (6.4 mL) 4 SF 2 SF = 2.390625 g/mL 2.4 g/mL 2 SF 18.9 g - 0.84 g 18.06 g 18.1 g Introduction to the Periodic Table • The vertical columns of the periodic table are called groups, or families. • Each group contains elements with similar chemical properties. • The horizontal rows of elements in the periodic table are called periods. • Physical and chemical properties change somewhat regularly across a period. The Unit Factor Method Simple but important method to get correct answers in word problems. Method to change from one set of units to another. Visual illustration of the idea. 48 B. Dimensional Analysis Steps: 1. Identify starting & ending units. 2. Line up conversion factors so units cancel. 3. Multiply all top numbers & divide by each bottom number. 4. Check units & answer. B. Dimensional Analysis How many milliliters are in 1.00 quart of milk? qt mL 1.00 qt 1L 1000 mL 1.057 qt 1L = 946 mL The Unit Factor Method Example 1-2: Express 627 milliliters in gallons. You do it! 51 The Unit Factor Method Example 1-2: Express 627 milliliters in gallons. ? gal =627 mL 1L 1.06qt 1gal ? gal = 627 mL ( )( )( ) 1000mL 1L 4qt ? gal = 0.166155 gal » 0.166 gal 52 The Unit Factor Method Example 1-3: Express 2.61 x 104 cm2 in ft2. Area is two dimensional, thus units must be in squared terms. 53 The Unit Factor Method Example 1-3: Express 2.61 x 104 cm2 in ft2. Area is two dimensional, thus units must be in squared terms. 1in 2 1ft 2 ? ft = 2.61 ´10 cm ( ) ( ) 2.54cm 12in 2 4 2 = 28.0938061 9 ft » 28.1 ft 2 2 54 Derived Units Combination of units. Volume amount of space occupied by an object length length length 1 cm3 = 1 mL (m3 or cm3) 1 dm3 = 1 L Density (kg/m3 or g/cm3) mass per volume M D= V Density and Specific Gravity density = mass/volume D=M/V How heavy something is for its size. The ratio of mass to volume for a substance. Independent of how much of it you have gold - high density 56 air low density. Density and Specific Gravity Example 1-6: Calculate the density of a substance if 742 grams of it occupies 97.3 cm3. 57 Density and Specific Gravity Example 1-6: Calculate the density of a substance if 742 grams of it occupies 97.3 cm3. 1 cm3 = 1 mL \ 97.3 cm3 = 97.3 mL density = m V 742 g density = 97.3 mL density = 7.63 g/mL 58 Density and Specific Gravity Example 1-7: Suppose you need 125 g of a corrosive liquid for a reaction. What volume do you need? (liquid’s density = 1.32 g/mL) You do it! 59 Density and Specific Gravity Example 1-7 Suppose you need 125 g of a corrosive liquid for a reaction. What volume do you need? (liquid’s density = 1.32 g/mL) m m density = \V = V density 125 g V= = 94.7 mL 1.32 g mL 60 Density and Specific Gravity density (substance ) Specific Gravity = density ( water ) Water’s density is essentially 1.00 at room T. Thus the specific gravity of a substance is very nearly equal to its density. Specific gravity has no units. 61 Density and Specific Gravity Example 1-8: A 31.0 gram piece of chromium is dropped into a graduated cylinder that contains 5.00 mL of water. The water level rises to 9.32 mL. What is the specific gravity of chromium? You do it 62 Density and Specific Gravity Example 1-8: A 31.0 gram piece of chromium is dropped into a graduated cylinder that contains 5.00 mL of water. The water level rises to 9.32 mL. What is the specific gravity of chromium? 31.0 g density of Cr 4.32 mL 7.17593 g 7.18 Specific Gravity of Cr 1.00 g mL g mL 7.18 g mL 7.18 mL 63 Density and Specific Gravity Example 1-9: A concentrated hydrochloric acid solution is 36.31% HCl and 63.69% water by mass. The specific gravity of the solution is 1.185. What mass of pure HCl is contained in 175 mL of this solution? You do it! 64 Density and Specific Gravity Example 1-9: A concentrated hydrochloric acid solution is 36.31% HCl and 63.69% water by mass. The specific gravity of the solution is 1.185. What mass of pure HCl is contained in 175 mL of this solution? Specific Gravity = 1.185 g g \ density = 1.185 = 1185 mL L 1.185 g sol' n 36.31 g HCl ? g HCl = 175 mL sol' n ´ ´ 1 mL 100.00 g solution 65 = 75.3 g HCl Heat and Temperature Heat and Temperature are not the same thing Temperature- measure of the average kinetic energy Temperature is which way heat will flow. (from hot to cold) 3 common temperature scales - all use water as a reference 66 Heat and Temperature Fahrenheit Celsius Kelvin MP water 32 oF 0.0 oC 273 K BP water 212 oF 100 oC 373 K 67 Relationships of the Three Temperature Scales Kelvin and Centigrade Relationships K = C + 273 or o o C = K - 273 68 How much it changes 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF 0ºC 100ºC 212ºF 32ºF Relationships of the Three Temperature Scales Fahrenheit and Centigrade Relationships 180 18 9 = = = 1.8 100 10 5 70 Relationships of the Three Temperature Scales 71 Relationships of the Three Temperature Scales Easy method to remember how to convert from Centigrade to Fahrenheit. 1. Double the Centigrade temperature. 2. Subtract 10% of the doubled number. 3. Add 32. 72 Heat and Temperature Example 1-10: Convert 211oF to degrees Celsius. 73 Heat and Temperature Example 1-10: Convert 211oF to degrees Celsius. F - 32 C= 1.8 211 - 32 o C= 1.8 o o 74 Heat and Temperature Example 1-11: Express 548 K in Celsius degrees. 75 Heat and Temperature Example 1-11: Express 548 K in Celsius degrees. o C = K - 273 o C = 548 - 273 o C = 275 76 Heat Transfer and the Measurement of Heat Heat is energy, ability to do work. SI unit J (Joule) calorie Amount of heat required to heat 1 g of water 1 oC 1 calorie = 4.184 J Calorie Large calorie, kilocalorie, dietetic calories Amount of heat required to heat 1 kg of water 1 oC English unit = BTU Specific Heat amount of heat required to raise the T of 1g of a substance by 1o C unit = J/goC 77 Heat Transfer and the Measurement of Heat Heat capacity amount of heat required to raise the T of 1 mole of a substance by 1oC unit = J/mol oC Heat transfer equation necessary to calculate amounts of heat amount of heat = amount of substance x specific heat x DT q = m ´ C ´ DT 78 Heat Transfer and the Measurement of Heat Example 1-12: Calculate the amt. of heat to raise T of 200.0 g of water from 10.0oC to 55.0oC 79 Heat Transfer and the Measurement of Heat Example 1-12: Calculate the amt. of heat to raise T of 200.0 g of water from 10.0oC to 55.0oC q m C DT 4.184 J o o ? J 200 g H 2 O (55.0 C 10.0 C) o 1 g H 2 O C 3.76 10 4 J or 37.6 kJ 80 Heat Transfer and the Measurement of Heat Example 1-13: Calculate the amount of heat to raise the temperature of 200.0 grams of mercury from 10.0oC to 55.0oC. Specific heat for Hg is 0.138 J/g oC. You do it! 81 Heat Transfer and the Measurement of Heat Example 1-13: Calculate the amount of heat to raise the temperature of 200.0 grams of mercury from 10.0oC to 55.0oC. Specific heat for Hg is 0.138 J/g oC. q = m ´ C ´ DT 0.138 J o o ? J = 200 g Hg ´ ´ (55.0 C 10.0 C) o (1 g Hg) C = 1.24 kJ 82 Heating Curve for 3 Substances Heating Curve Which substance has the largest specific heat? 140 120 Temperature (celsius degree) 100 80 Substance 1 Substance 2 Substance 3 60 40 20 0 0 50 100 150 200 250 300 Which substance’s T will decrease the most after the heat has been removed? Tim e (s) 83 Heating Curve for 3 Substances Temperature (deg C) Heating Curve 140 120 100 80 60 40 20 0 Substance 1 Substance 2 Substance 3 0 200 400 600 Time (s) 84 Synthesis Question It has been estimated that 1.0 g of seawater contains 4.0 pg of Au. The total mass of seawater in the oceans is 1.6x1012 Tg, If all of the gold in the oceans were extracted and spread evenly across the state of Georgia, which has a land area of 58,910 mile2, how tall, in feet, would the pile of Au be? Density of Au is 19.3 g/cm3. 1.0 Tg = 1012g. 85 Synthesis Question 12 10 g 24 (1.6 ´ 10 Tg) ( ) = 1.6 ´ 10 g of H 2 O Tg 12 -12 4.0 ´ 10 g Au 12 (1.6 ´ 10 g of H 2 O)( ) = 6.4 ´ 10 g Au g of H 2 O 24 86 Synthesis Question 12 10 g 12 (1.6 ´ 10 Tg) ( ) = 1.6 ´ 10 24 g of H 2 O Tg -12 4.0 ´ 10 g Au 24 (1.6 ´ 10 g of H 2 O)( ) = 6.4 ´ 1012 g Au g of H 2 O 3 æ ö 1cm 12 ÷÷ = 3.3 ´ 1011 cm 3 Au 6.4 ´ 10 g Au çç è 19.3 g Au ø æ 5280 ft öæ 12 in öæ 2.54 cm ö ÷÷çç ÷÷çç ÷÷ = 160,934 cm (1 mile)çç è 1 mile øè 1 ft øè 1 in ø ( ) (160,934 cm )3 = (1 mile)3\ 4.16 ´ 1015 cm 3 = 1 mile3 87 Synthesis Question 3 æ ö 1 mile 11 3 -5 3 ÷ (3.3 ´ 10 cm Au)çç = 7.96 ´ 10 mile 15 3 ÷ 4.16 ´ 10 cm è ø æ 5280 ft ö 7.96 ´ 10 -5 mile 3 -9 -6 ç ÷ = (1.35 ´ 10 mile) = 7.13 ´ 10 ft 2 ç ÷ 58,910 mile è 1 mile ø 88