General, Organic, and Biological Chemistry. Fourth Edition Karen Timberlake. Chapter 2. Energy and Matter Pearson Education, Inc.

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1 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2013 Pearson Education, Inc.

2 Section 2.1 Energy Energy is the ability to do work or transfer heat. Work done on matter implies a change of position or movement can be classified as either potential (postional) or kinetic (motion). comes from the food we eat and enables us to do work Pearson Education, Inc. Chapter 2, Section 1 2

3 Potential Energy (PE) is the energy stored for use at a later time. Examples: water behind a dam, a compressed spring, energy stored in the chemical bonds in fossil fuels or food Kinetic Energy (KE) is the energy of matter in motion. Examples: swimming, water flowing over a dam, working out, burning gasoline Kinetic and Potential Energy are interchangable i.e. KE can be converted to PE and vice versa 2013 Pearson Education, Inc. Chapter 2, Section 1 3

4 Learning Check Identify each of the following as potential energy or kinetic energy. A. roller blading B. a peanut butter and jelly sandwich C. mowing the lawn D. gasoline in the gas tank 2013 Pearson Education, Inc. Chapter 2, Section 1 4

5 The Concept of Heat Heat is also called thermal energy. is associated with the motion of particles. Adding heat to food increases the motion of the particles, which makes the food hot. Do not confuse temperature with heat, they are not the same thing 2013 Pearson Education, Inc. Chapter 2, Section 1 5

6 Units for Measuring Energy or Heat Heat is measured in joules or calories. A food Calorie is actually a kilocalorie (1000 calories) 2013 Pearson Education, Inc. Chapter 2, Section 1 6

7 Learning Check How many calories are obtained from a pat of butter if it provides 150 J of energy when metabolized? A. 36 cal B. 150 cal C. 630 cal 2013 Pearson Education, Inc. Chapter 2, Section 1 7

8 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.2 Temperature 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 8

9 Temperature Scales In science, temperature is measured in Celsius ( o C) units. Temperature scales are Fahrenheit, Celsius, and Kelvin. have reference points for the boiling and freezing points of water Pearson Education, Inc. Chapter 2, Section 2 9

10 Learning Check 1. What is the temperature of freezing water? A. 0 F B. 0 C C. 0 K 2. What is the temperature of boiling water? A. 100 F B. 32 F C. 373 K 3. How many Celsius units are between the boiling and freezing points of water? A. 100 B. 180 C Pearson Education, Inc. Chapter 2, Section 1 10

11 Celsius to Fahrenheit Formula On the Fahrenheit scale, there are 180 F between the freezing and boiling points, and on the Celsius scale, there are = 100 C In the formula for the Fahrenheit temperature, adding 32 adjusts the zero point of water from 0 C to 32 F Pearson Education, Inc. Chapter 2, Section 1 11

12 Fahrenheit to Celsius Formula T C is obtained by rearranging the equation for T F. Subtract 32 from both sides. Divide by Pearson Education, Inc. Chapter 2, Section 1 12

13 Kelvin Scale The coldest temperature possible is o C, which is called absolute zero. The Kelvin scale is based on absolute zero. To convert between Kelvin and Celsius: T K = T C Pearson Education, Inc. Chapter 2, Section 1 13

14 Kelvin Celsius Fahrenheit 2013 Pearson Education, Inc. Chapter 2, Section 1 14

15 Solving a Temperature Problem A person with hypothermia has a body temperature of 34.8 C. What is that temperature in F? Step 1 State the given and needed quantities. Analyze the Problem. Given Need Step 2 Write a temperature equation Pearson Education, Inc. Chapter 2, Section 2 15

16 Solving a Temperature Problem A person with hypothermia has a body temperature of 34.8 C. What is that temperature in F? Step 3 Substitute in the known values and calculate the new temperature Pearson Education, Inc. Chapter 2, Section 2 16

17 Learning Check A pepperoni pizza is baked at 455 F. What temperature is needed on the Celsius scale? A. 423 C B. 235 C C. 221 C 2013 Pearson Education, Inc. Chapter 2, Section 1 17

18 Learning Check On a cold winter day, the temperature is 15 C. What is the temperature in F? A. 19 F B. 59 F C. 5 F 2013 Pearson Education, Inc. Chapter 2, Section 1 18

19 Learning Check What is normal body temperature of 37 C in Kelvin? A. 236 K B. 310 K C. 342 K 2013 Pearson Education, Inc. Chapter 2, Section 1 19

20 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.3 Classification of Matter 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 20

21 Matter Matter is anything that has mass and occupies space. makes up the things we see everyday, such as water, wood, cooking pans, clothes, and shoes. can be classified as a pure substance or mixture. Matter Mixture Pure Substance 2013 Pearson Education, Inc. Chapter 2, Section 2 21

22 Pure Substances A pure substance has a fixed or constant composition. can be classified as an element or compound. Pure Substance Element one type of atom Compound two or more elements chemically combined 2013 Pearson Education, Inc. Chapter 2, Section 2 22

23 Elements Elements are pure substances that contain atoms of only one type. Examples: copper (Cu) lead (Pb) aluminum (Al) 2013 Pearson Education, Inc. Chapter 2, Section 2 23

24 Compounds Compounds contain two or more elements that are chemically combined in a definite ratio. Examples: salt (NaCl) table sugar (C 12 H 22 O 11 ) water (H 2 O) 2013 Pearson Education, Inc. Chapter 2, Section 2 24

25 Elements in a Compound Table salt is a compound that contains the elements sodium and chlorine Pearson Education, Inc. Chapter 2, Section 2 25

26 Mixtures A mixture is matter that consists of two or more substances that are physically mixed, not chemically combined. a composition that is not constant. substances that can be separated by physical methods Pearson Education, Inc. Chapter 2, Section 1 26

27 Physical Separation of A Mixture The physical separation of a mixture involves only physical changes. occurs when pasta and water are separated with a strainer Pearson Education, Inc. Chapter 2, Section 2 27

28 Separation of A Mixture in Lab The physical separation of a mixture in a chemistry lab may include: filtration chromatography 2013 Pearson Education, Inc. Chapter 2, Section 2 28

29 Types of Mixtures Mixtures are classified by their composition. called homogeneous when they are uniform. called heterogeneous when they are not uniform. Mixtures Homogeneous Mixture Uniform Heterogeneous Mixture Not uniform 2013 Pearson Education, Inc. Chapter 2, Section 2 29

30 Homogeneous Mixtures In a homogeneous mixture, the composition is uniform throughout, and different parts of the mixture are not visible Pearson Education, Inc. Chapter 2, Section 2 30

31 Heterogeneous Mixtures In a heterogeneous mixture, the composition is not uniform; it varies from one part of the mixture to another, and different parts of the mixture are visible Pearson Education, Inc. Chapter 2, Section 2 31

32 Classification of Matter Matter is organized by its components: elements, compounds, and mixtures Pearson Education, Inc. Chapter 2, Section 1 32

33 Learning Check Identify each of the following as a pure substance or a mixture. A. pasta and tomato sauce B. aluminum foil C. helium D. air 2013 Pearson Education, Inc. Chapter 2, Section 1 33

34 Learning Check Identify each of the following as a homogeneous or heterogeneous mixture. A. hot fudge sundae B. a clear shampoo C. sugar water D. peach pie 2013 Pearson Education, Inc. Chapter 2, Section 1 34

35 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.4 States and Properties of Matter 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 35

36 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.4 States and Properties of Matter 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 36

37 Solids Solids have a definite shape. a definite volume. particles that are close together in a rigid pattern. particles that vibrate slowly in their fixed positions. Amethyst, a solid, is a purple form of quartz (SiO 2 ) Pearson Education, Inc. Chapter 2, Section 1 37

38 Liquids Liquids have a definite volume, but not a definite shape. the same shape as their container. particles that are close together, but mobile. particles that move slowly in random directions Pearson Education, Inc. Chapter 2, Section 1 38

39 Gases Gases do not have a definite shape. do not have a definite volume. take the same shape and volume as their container. have particles that are far apart. are composed of fast moving particles that have little attraction to each other Pearson Education, Inc. Chapter 2, Section 1 39

40 A Comparison of Solids, Liquids, and Gases 2013 Pearson Education, Inc. Chapter 2, Section 4 40

41 Learning Check Identify each as a (S) solid, (L) liquid, or (G) gas. A. It has a definite volume, but takes the shape of the container. B. Its particles are moving very rapidly. C. It fills the volume of a container. D. It has particles in a fixed arrangement. E. It has particles that are close together and are mobile Pearson Education, Inc. Chapter 2, Section 1 41

42 Physical Properties are observed or measured without affecting the identity of a substance. include shape, physical state, boiling and freezing points, density, and color of that substance Pearson Education, Inc. Chapter 2, Section 1 42

43 Physical Change A physical change occurs in a substance if there is a change in the state. a change in the physical shape. no change in the identity and composition of the substance. Example ice melting, water boiling, a rock being crushed 2013 Pearson Education, Inc. Chapter 2, Section 2 43

44 Physical Changes and Water On Earth, water is found in all three physical states, solid, liquid, and gas Water changes state from a solid to a liquid and from a liquid to a gas as heat is added. Q: Is heat added or released when liquid water freezes? 2013 Pearson Education, Inc. Chapter 2, Section 2 44

45 Change of State: Melting and Freezing At the melting point, a solid is converted to a liquid. At the freezing point, a liquid is converted to a solid Pearson Education, Inc. Chapter 2, Section 2 45

46 Change of State: Evaporation and Condensation At the boiling point, a liquid is converted to a gas. At the same temperature, a gas is converted to a liquid as heat is removed Pearson Education, Inc. Chapter 2, Section 2 46

47 Heating Curve A heating curve represents changes in temperature and physical state as heat is added to a substance. A horizontal line represents a phase change; a diagonal line represents an increase in the temperature of the substance Pearson Education, Inc. Chapter 2, Section 2 47

48 Cooling Curve A cooling curve represents changes in temperature and physical state as heat is removed from a substance. A horizontal line represents a phase change; a diagonal line represents a decrease in the temperature of the substance Pearson Education, Inc. Chapter 2, Section 2 48

49 Change of State: Sublimation and Deposition Sublimation is the process that describes the physical change of a solid directly to a gas. Deposition is the process that describes the physical change of a gas directly to a solid Pearson Education, Inc. Chapter 2, Section 2 49

50 Examples of Physical Change 2013 Pearson Education, Inc. Chapter 2, Section 2 50

51 Chemical Properties and Chemical Change Chemical properties describe the ability of a substance to change into a new substance. During a chemical change a new substance forms that has a new composition. new chemical and physical properties Pearson Education, Inc. Chapter 2, Section 1 51

52 Summary of Chemical and Physical Properties and Changes 2013 Pearson Education, Inc. Chapter 2, Section 1 52

53 Learning Check Classify each of the following as a (1) physical change or (2) chemical change. A. burning a candle B. ice melting on the street C. toasting a marshmallow D. cutting a pizza E. polishing a silver bowl 2013 Pearson Education, Inc. Chapter 2, Section 1 53

54 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.5 Specific Heat 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 54

55 Specific Heat Specific heat is different for different substances. is the amount of heat that raises the temperature of 1 g of a substance by 1 C. is represented by the equation, where ΔT = the change in temperature. in the SI system, has units of J/g C. in the metric system, has units of cal/g C Pearson Education, Inc. Chapter 2, Section 1 55

56 Learning Check 1. If the same amount of heat is added, what will occur in a substance with a lower specific heat? A. a smaller increase in temperature B. a greater increase in temperature 2. When ocean water warms, what happens to the surrounding air? A. cools B. warms C. stays the same 2013 Pearson Education, Inc. Chapter 2, Section 1 56

57 Guide to Calculating Specific Heat 2013 Pearson Education, Inc. Chapter 2, Section 1 57

58 Calculating Specific Heat What is the specific heat of a metal if 24.8 g absorbs 65.7 cal of energy and the temperature rises from 20.2 C to 24.5 C? Step 1 State the given and needed quantities. Analyze the Problem. Given Need 2013 Pearson Education, Inc. Chapter 2, Section 1 58

59 Calculating Specific Heat What is the specific heat of a metal if 24.8 g absorbs 65.7 cal of energy and the temperature rises from 20.2 C to 24.5 C? Step 2 Write the relationship for specific heat. Step 3 Set up the problem to calculate SH Pearson Education, Inc. Chapter 2, Section 1 59

60 Heat Equation Rearranging the specific heat expression gives the heat equation: The amount of heat lost or gained by a substance is calculated from the mass of substance (g), the temperature change ( T), or the specific heat of the substance (cal/g C) or (J/g C) Pearson Education, Inc. Chapter 2, Section 1 60

61 Guide to Calculations Using Specific Heat 2013 Pearson Education, Inc. Chapter 2, Section 1 61

62 Sample Calculation for using Specific Heat A hot-water bottle contains 750 g of water at 65 C. If the water cools to body temperature (37 C), how many calories of heat could be transferred to sore muscles? Step 1 State the given and needed quantities. Analyze the Problem. Given Need 2013 Pearson Education, Inc. Chapter 2, Section 1 62

63 Sample Calculation for using Specific Heat A hot-water bottle contains 750 g of water at 65 C. If the water cools to body temperature (37 C), how many calories of heat could be transferred to sore muscles? Step 2 Calculate the temperature change ( T). Step 3 Write the heat equation Pearson Education, Inc. Chapter 2, Section 1 63

64 Sample Calculation for using Specific Heat A hot-water bottle contains 750 g of water at 65 C. If the water cools to body temperature (37 C), how many calories of heat could be transferred to sore muscles? Step 4 Substitute in the given values and solve, making sure units cancel Pearson Education, Inc. Chapter 2, Section 1 64

65 Learning Check How many kilojoules are needed to raise the temperature of 325 g of water from 15.0 C to 77.0 C? A kj B kj C. 105 kj 2013 Pearson Education, Inc. Chapter 2, Section 1 65

66 General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake Chapter 2 Energy and Matter 2.6 Energy and Nutrition 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 2, Section 1 66

67 Calorimeters A calorimeter is used to calculate the energy value of food. contains a reaction chamber and thermometer in water. indicates the amount of heat lost by food by observing the temperature increase of the water. Heat released from burning a food sample in a calorimeter is used to determine the energy value of the food Pearson Education, Inc. Chapter 2, Section 2 67

68 Energy and Nutrition On food labels, energy is shown as the nutritional Calorie, written with a capital C. In countries other than the United States, energy is shown in kilojoules (kj) Pearson Education, Inc. Chapter 2, Section 2 68

69 Energy Values for 3 Food Types The energy (caloric) values of food are the kilojoules or kilocalories obtained from burning 1 g of a carbohydrate, fat, or protein Pearson Education, Inc. Chapter 2, Section 2 69

70 Calculating Food Energy Values When a 4.0 g sample of fat was combusted in a calorimeter, 164 kj was absorbed. Calculate the energy value of the fat in kj/g. Solution: Because 164 kj was produced by the combustion of 4.0 g of fat, we calculate the energy value with the equation below Pearson Education, Inc. Chapter 2, Section 1 70

71 Energy Requirements The amount of energy needed each day depends on age, gender, and level of physical activity. If food intake exceeds energy use, a person gains weight. If food intake is less than energy use, a person loses weight Pearson Education, Inc. Chapter 2, Section 2 71

72 Learning Check A cup of whole milk contains 12 g of carbohydrates, 9.0 g of fat, and 9.0 g of protein. How many kcal (Cal) does a cup of milk contain? (Round to the nearest 10 kcal.) A. 50 kcal (50 Cal) B. 80 kcal (80 Cal) C. 150 kcal (150 Cal) 2013 Pearson Education, Inc. Chapter 2, Section 1 72