CHAPTER ONE The Foundations of Chemistry Chapter Outline 1. 2. 3. 4. 5. 6. 7. Matter and Energy States of Matter Chemical and Physical Properties Chemical and Physical Changes Mixtures, Substances, Compounds, and Elements Measurements in Chemistry Units of Measurement 2 Chapter Outline 8. 9. 10. 11. 12. 13. Use of Numbers The Unit Factor Method (Dimensional Analysis) Percentage Density and Specific Gravity Heat and Temperature Heat Transfer and the Measurement of Heat 3 Matter and Energy - Vocabulary Chemistry Matter Anything that has mass and occupies space. Energy Science that describes matter – its properties, the changes it undergoes, and the energy changes that accompany those processes The capacity to do work or transfer heat. Scientific (natural) law A general statement based the observed behavior of matter to which no exceptions are known. 4 Natural Laws Law of Conservation of Mass Law of Conservation of Energy Law of Conservation of Mass-Energy Einstein’s Relativity E=mc2 5 Scientific Method Observation Hypothesis Observation or experiment Theory Observation or experiment Law 6 States of Matter Solids 7 States of Matter Solids Liquids 8 States of Matter Solids Liquids Gases 9 States of Matter Change States heating cooling 10 States of Matter Illustration of changes in state requires energy 11 Chemical and Physical Properties Chemical Properties - chemical changes Physical Properties - physical changes rusting or oxidation chemical reactions changes of state density, color, solubility Extensive Properties - depend on quantity Intensive Properties - do not depend on quantity 12 Mixtures, Substances, Compounds, and Elements Substance Elements matter in which all samples have identical composition and properties substances that cannot be decomposed into simpler substances via chemical reactions Elemental symbols found on periodic chart 13 Mixtures, Substances, Compounds, and Elements 14 Mixtures, Substances, Compounds, and Elements Compounds substances composed of two or more elements in a definite ratio by mass can be decomposed into the constituent elements Water is a compound that can be decomposed into simpler substances – hydrogen and oxygen 15 Mixtures, Substances, Compounds, and Elements 16 Mixtures, Substances, Compounds, and Elements Mixtures composed of two or more substances homogeneous mixtures heterogeneous mixtures 17 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 18 Measurements in Chemistry Metric Prefixes Name mega kilo deka deci centi Symbol M k da d c Multiplier 106 103 10 10-1 10-2 19 Measurements in Chemistry Metric Prefixes Name milli micro nano pico femto Symbol m n p f Multiplier 10-3 10-6 10-9 10-12 10-15 20 Units of Measurement Definitions Mass measure of the quantity of matter in a body Weight measure of the gravitational attraction for a body 21 Units of Measurement Common Conversion Factors Length Volume 1 m = 39.37 inches 2.54 cm = 1 inch 1 liter = 1.06 qt 1 qt = 0.946 liter See Table 1-7 for more conversion factors 22 Use of Numbers Exact numbers Accuracy 1 dozen = 12 things for example how closely measured values agree with the correct value Precision how closely individual measurements agree with each other 23 Use of Numbers Significant figures digits believed to be correct by the person making the measurement Measure a mile with a 6 inch ruler vs. surveying equipment Exact numbers have an infinite number of significant figures 12.000000000000000 = 1 dozen because it is an exact number 24 Use of Numbers Significant Figures - Rules Leading zeroes are never significant 0.000357 has three significant figures Trailing zeroes may be significant must specify significance by how the number is written 1300 nails - counted or weighed? Use scientific notation to remove doubt 2.40 x 103 has ? significant figures 25 Use of Numbers Scientific notation for logarithms take the log of 2.40 x 103 log(2.40 x 103) = 3.380 How many significant figures? Imbedded zeroes are always significant 3.0604 has five significant figures 26 Use of Numbers Piece of Black Paper – with rulers beside the edges 2 3 4 5 6 7 8 9 10 11 12 13 14 9 8 7 6 5 4 3 2 1 1 27 Use of Numbers Piece of Paper Side B – enlarged 11 How long is the paper to the best of your ability to measure it? 12 13 14 28 5 6 Use of Numbers Piece of Paper Side A – enlarged 7 How wide is the paper to the best of your ability to measure it? 8 9 29 Use of Numbers Determine the area of the piece of black paper using your measured values. Compare your answer with your classmates. Where do your answers differ in the numbers? Significant figures rules for multiplication and division must help us determine where answers would differ. 30 Use of Numbers Multiplication & Division rule Easier of the two rules Product has the smallest number of significant figures of multipliers 31 Use of Numbers Multiplication & Division rule Easier of the two rules Product has the smallest number of significant figures of multipliers 4.242 x 1.23 5.21766 round off to 5.22 32 Use of Numbers Multiplication & Division rule Easier of the two rules Product has the smallest number of significant figures of multipliers 4.242 x 1.23 2.7832 x 1.4 5.21766 round off to 5.22 3.89648 round off to 3.9 33 Use of Numbers Determine the perimeter of the piece of black paper using your measured values. Compare your answer with your classmates. Where do your answers differ in the numbers? Significant figures rules for addition and subtraction must help us determine where answers would differ. 34 Use of Numbers Addition & Subtraction rule More subtle than the multiplication rule Answer contains smallest decimal place of the addends. 35 Use of Numbers Addition & Subtraction rule More subtle than the multiplication rule Answer contains smallest decimal place of the addends. 3.6923 1.234 2.02 6.9463 round off to 6.95 36 Use of Numbers Addition & Subtraction rule More subtle than the multiplication rule Answer contains smallest decimal place of the addends. 3.6923 2.02 8.7937 2.123 6.9463 round off to 6.95 6.6707 round off to 6.671 1.234 37 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. 38 The Unit Factor Method Change from a following rules. to a by obeying the 39 The Unit Factor Method 1. Change from a to a by obeying the following rules. Must use colored fractions. 40 The Unit Factor Method 1. 2. Change from a to a by obeying the following rules. Must use colored fractions. The box on top of the fraction must be the same color as the next fraction’s bottom box. 41 The Unit Factor Method R Fractions to choose from R O B O B B O R O B B B 42 The Unit Factor Method O R R Fractions to choose from R O B O B B O R O B B B 43 The Unit Factor Method O B R O R Fractions to choose from R O B O B B O R O B B B 44 The Unit Factor Method O B B R B R O B Fractions to choose from R O B O B B O R O B B B 45 The Unit Factor Method O B B R B R O B Fractions to choose from R O B O B B O R O B B B 46 The Unit Factor Method O B B R B R O B Fractions to choose from R O B O B B O R O B B B 47 The Unit Factor Method O B B R B R O B Fractions to choose from R O B O B B O R O B B B 48 The Unit Factor Method colored fractions represent unit factors 1 ft = 12 in becomes 1 ft 12 in or 12 in 1 ft Example 1-1: Express 9.32 yards in millimeters. 49 The Unit Factor Method 9.32 yd ? mm 3ft 9.32 yd ( ) 1yd 50 The Unit Factor Method 9.32 yd ? mm 3ft 12in 9.32 yd ( ) ( ) 1yd 1ft 51 The Unit Factor Method 9.32 yd ? mm 3ft 12in 2.54cm 9.32 yd ( )( )( ) 1yd 1ft 1in 52 The Unit Factor Method 9.32 yd ? mm 3ft 12in 2.54cm 10mm 9.32 yd ( )( )( )( ) 8.52 103 mm 1yd 1ft 1in 1cm 53 The Unit Factor Method 9.32 yd ? mm 3ft 12in 2.54cm 10mm 9.32 yd ( )( )( )( ) 8.52 103 mm 1yd 1ft 1in 1cm O B B T R T R O B B 54 The Unit Factor Method Example 1-2: Express 627 milliliters in gallons. You do it! 55 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 56 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 57 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 1 in ? ft 2.61 10 cm ( ) 2.54 cm 2 4 2 common mistake 58 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 1 in ? ft 2.61 10 cm ( ) 2.54 cm 2 4 2 O R P 59 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 1 in 2 4 2 2 ? ft 2.6110 cm ( ) 2.54 cm O R R 60 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 1 in 2 4 2 2 1 ft 2 ? ft 2.61 10 cm ( ) ( ) 2.54 cm 12 in 61 The Unit Factor Method Area is two dimensional thus units must be in squared terms. Example 1-3: Express 2.61 x 104 cm2 in ft2. 1in 2 1ft 2 ? ft 2.6110 cm ( ) ( ) 2.54cm 12in 2 4 2 28.09380619 ft 28.1 ft 2 2 62 The Unit Factor Method Volume is three dimensional thus units must be in cubic terms. Example 1-4: Express 2.61 ft3 in cm3. You do it! 63 The Unit Factor Method Volume is three dimensional thus units must be in cubic terms. Example 1-4: Express 2.61 ft3 in cm3. 12 in 3 2.54 cm 3 ? cm 2.61 ft ( ) ( ) 1 ft 1 in 3 3 73906.9696 cm 7.39 10 cm 3 4 3 64 Percentage Percentage is the parts per hundred of a sample. Example 1-5: A 335 g sample of ore yields 29.5 g of iron. What is the percent of iron in the ore? You do it! 65 Percentage Percentage is the parts per hundred of a sample. Example 1-5: A 335 g sample of ore yields 29.5 g of iron. What is the percent of iron in the ore? grams of iron ? % iron x 100% grams of ore 29.5 g Fe x 100% 335 g ore 8.81% 66 Density and Specific Gravity density = mass/volume What is density? Why does ice float in liquid water? 67 Density and Specific Gravity density = mass/volume What is density? Why does ice float in liquid water? H H H C H H H C H H 68 Density and Specific Gravity Example 1-6: Calculate the density of a substance if 742 grams of it occupies 97.3 cm3. 1 cm 1 mL 97.3 cm 97.3 mL density m V 3 3 69 Density and Specific Gravity Example 1-6: Calculate the density of a substance if 742 grams of it occupies 97.3 cm3. 1 cm 3 1 mL 97.3 cm 3 97.3 mL density m V 742 g density 97.3 mL density 7.63 g/mL 70 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! 71 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 72 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 73 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. 74 Density and Specific Gravity Example 1-8: A 31.0 gram piece of chromium is dipped 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 75 Density and Specific Gravity Example1-8: A 31.0 gram piece of chromium is dipped 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? Volume of Cr 9.32 mL - 5.00 mL 4.32 mL 31.10 g density of Cr 4.32 mL 76 Density and Specific Gravity Example1-8: A 31.0 gram piece of chromium is dipped 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? 31.10 g density of Cr 4.32 mL 7.19907 g mL 7.20 g mL 7.20 g mL Specific Gravity of Cr 7.20 g 1.00 mL 77 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! 78 Density and Specific Gravity Some Possible Unit Factors from this Problem 36.31 g HCl 36.31 g HCl 63.69 g H 2 O or or 63.69 g H 2 O 100.00 g solution 100.00 g solution 79 Density and Specific Gravity Specific Gravity 1.185 from problem g g density 1.185 1185 mL L 80 Density and Specific Gravity 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 75.3 g HCl 81 Try This One… Battery acid is 40.0% sulfuric acid and 60% water by mass. Its specific gravity is 1.31. 82 Solution: From the given specific value number 1.31 We may write Density = 1.31g/mL Next… 83 The solution is 40% sulfuric acid and 60% water by mass…from this information we get… 40.0 g 100 g sulfuric acid solution Because 100g of solution contains 40.0 g of sulfuric acid 84 We can now solve the problem: __g H2SO4 = 1.31g soln 40 g H2SO4 100.00mL solution x x 52.4 g H2SO4 1 mL soln 100 g soln 85 Heat and Temperature Heat and Temperature are not the same thing T is a measure of the intensity of heat in a body 3 common temperature scales - all use water as a reference 86 Heat and Temperature Heat and Temperature are not the same thing T is a measure of the intensity of heat in a body 3 common temperature scales - all use water as a reference 87 Heat and Temperature Fahrenheit Celsius Kelvin MP water 32 oF 0.0 oC 273 K BP water 212 oF 100 cC 373 K 88 Relationships of the Three Temperature Scales Kelvin and Centigrade Relationsh ips K C 273 or o o C K 273 89 Relationships of the Three Temperature Scales Fahrenheit and Centigrade Relationsh ips 180 18 9 1.8 100 10 5 90 Relationships of the Three Temperature Scales Fahrenheit and Centigrade Relationsh ips 180 18 9 1.8 100 10 5 o F 1.8 o C 32 or F 32 C 1.8 o o 91 Relationships of the Three Temperature Scales 1. 2. 3. Easy method to remember how to convert from Centigrade to Fahrenheit. Double the Centigrade temperature. Subtract 10% of the doubled number. Add 32. 92 Heat and Temperature Example 1-10: Convert 211oF to degrees Celsius. F 32 C 1.8 211 32 o C 1.8 o o 93 Heat and Temperature Example 1-11: Express 548 K in Celsius degrees. o C K 273 o C 548 273 o C 275 94 Heat Transfer and The Measurement of Heat 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 1oC units = J/goC 95 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 units = J/mol oC Example 1-12: Calculate the amt. of heat to raise T of 200.0 g of water from 10.0oC to 55.0oC 96 Heat Transfer and the Measurement of Heat Heat transfer equation necessary to calculate amounts of heat amount of heat = amount of substance x specific heat x DT q m C DT 97 Heat Transfer and the Measurement of Heat Heat transfer equation necessary to calculate amounts of heat amount of heat = amount substance x specific heat x DT q m C DT 4.184 J o o ? J 200 g H 2 O (55.0 C 10.0 C) 1 g H 2O 98 Heat Transfer and the Measurement of Heat Heat transfer equation necessary to calculate amounts of heat amount of heat = amount substance x specific heat x DT q m C DT 4.184 J ? J 200 g H 2 O (55.0 o C 10.0o C) 1 g H 2O 3.76 10 4 J or 37.6 kJ 99 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! 100 Heat Transfer and the Measurement of Heat Example 1-13: Calculate the amount of heat to raise T of 200.0 g of Hg 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 Requires 30.3 times more heat for water 4.184 is 30.3 times greater than 0.138 101 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) 102 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) 103