ENERGY

1
CHAPTER 2

• ENERGY MATTER

2
Section 3

• The purpose of this section is to discuss the
  conservation of matter during physical and
  chemical processes and then to explain the nature
  of these processes.

3
Learning TargetsSection 3

• I can describe the four states of matter both at
  the macroscopic level and the atomic level,
  including models of each state.
• I can state the law of conservation of matter.
• I can classify properties of matter as either
  physical or chemical.
• I can describe the differences between physical
  changes and chemical changes.

4
Matter

• Anything that has mass and occupies space (volume)

5
4 States of Matter

• Solid
• Liquid
• Gas
• Plasma

6
Solids

• Macroscopic
• Definite shape
• Definite volume
• Incompressible
• Molecular
• Particles have very low KE
• Particles packed closely high density

7
Liquids

• Macroscopic
• No definite shape
• Definite volume
• Incompressible
• Molecular
• Particles have low KE
• Particles spaced closer than a gas but further
  than a solid high density

8
Gas

• Macroscopic
• No definite shape
• No definite volume
• Compressible
• Molecular
• Particles have high KE
• Particles spaced far apart low density
• Particles have collisions

9
Plasma

• High temperature state of matter in which atoms
  lose most of their electrons
• Very high KE
• Low density

10
Changes of State

• Transitions from one state of matter to another
  (occur through temperature changes)
• Boil liquid to a gas
• Freeze liquid to a solid

11
Sodium as a Solid, Liquid Gas
12
Mercury in 3 States
13
Conservation of Matter

• Matter is neither created nor destroyed

14
2 Properties of Matter

• Physical Properties
• Chemical Properties

15
Physical Properties

• Characteristics of matter that can be observed
  without altering the identity of the substance
• e.g. density, color, melting point

16
Chemical Properties

• Characteristics of matter that cannot be observed
  without altering the identity of the substance
• e.g. flammability, reactivity

17
Practice ProblemsClassify each of the following
as a physical or chemical property.

• The boiling point of a certain alcohol is 78 oC.

18
Practice ProblemsClassify each of the following
as a physical or chemical property.

• The boiling point of a certain alcohol is 78 oC.
• Physical Property

19
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Diamonds are very hard.

20
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Diamonds are very hard.
• Physical Property

21
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Sugar ferments to form alcohol.

22
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Sugar ferments to form alcohol.
• Chemical Property

23
Practice ProblemsClassify each of the following
as a physical or chemical property.

• A metal wire conducts electric current.

24
Practice ProblemsClassify each of the following
as a physical or chemical property.

• A metal wire conducts electric current.
• Physical Property

25
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Gallium metal melts in your hand.

26
Practice ProblemsClassify each of the following
as a physical or chemical property.

• Gallium metal melts in your hand.
• Physical Property

27
Practice ProblemsClassify each of the following
as a physical or chemical property.

• This page is white.

28
Practice ProblemsClassify each of the following
as a physical or chemical property.

• This page is white.
• Physical Property

29
Practice ProblemsClassify each of the following
as a physical or chemical property.

• The copper sheets that form the skin of the
  Statue of Liberty have acquired a greenish
  coating over the years.

30
Practice ProblemsClassify each of the following
as a physical or chemical property.

• The copper sheets that form the skin of the
  Statue of Liberty have acquired a greenish
  coating over the years.
• Chemical Property

31
Changes in Matter

• Physical Changes
• Chemical Changes

32
Physical Changes

• Changes which do not alter the identity of the
  substance
• Physical chemical properties remain the same
• e.g. crushing, tearing, changes in state

33
Chemical Changes

• Changes which alter the identity of the substance
• Physical chemical properties are different from
  the original substance
• e.g. burning, cooking

34
Physical or Chemical Change?

• Has the change altered the identity of the
  substance?
• Yes chemical
• No physical
• Are the physical and/or chemical properties
  different from the original substance?
• Yes chemical
• No physical

35
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Iron metal is melted.

36
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Iron metal is melted.
• Physical Change

37
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Iron combines with oxygen to form rust.

38
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Iron combines with oxygen to form rust.
• Chemical Change

39
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Wood burns in air.

40
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Wood burns in air.
• Chemical Change

41
Practice ProblemsClassify each of the following
as a physical or chemical change.

• A rock is broken into small pieces.

42
Practice ProblemsClassify each of the following
as a physical or chemical change.

• A rock is broken into small pieces.
• Physical Change

43
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Milk turns sour.

44
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Milk turns sour.
• Chemical Change

45
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Wax is melted over a flame and then catches fire
  and burns.

46
Practice ProblemsClassify each of the following
as a physical or chemical change.

• Wax is melted over a flame and then catches fire
  and burns.
• Both Physical and Chemical Changes

47
Section 4

• The purpose of this section is to distinguish
  between elements and compounds. Both elements and
  compounds are examples of pure substances.
  Compounds can be broken into simpler substances,
  but elements cannot.

48
Learning TargetsSection 4

• I can explain the difference between an element
  and a compound.
• I can explain why compounds are considered pure
  substances.
• I can classify pure substances as either elements
  or compounds.

49
Classifying Matter

• Matter can be classified as either a pure
  substance or a mixture

50
Pure Substances

• Have a unique set of physical and chemical
  properties
• A pure substance always has the same composition
  regardless of the sample size
• 2 Types
• Elements
• Compounds

51
Elements

• A substance which cannot be broken down
  chemically into a simpler substance
• Composed of one type of atom
• Atom the simplest unit of an element

bromine
silver
52
Compounds

• A substance that contains two or more elements
  that are chemically combined in a fixed
  proportion
• Can be chemically broken down into elements

53
Practice Problems

• What is an element?

54
Practice Problems

• What is an element?
• A substance made up of one type of atom that
  cannot be chemically broken down into a simpler
  substance.

55
Practice Problems

• What is the difference between an element and a
  compound?

56
Practice Problems

• What is the difference between an element and a
  compound?
• An element is made up of one type of atom while a
  compound contains 2 or more types of atoms
  chemically combined. An element cannot be
  chemically broken down while a compound can be
  chemically broken down into elements.

57
Practice Problems

• Why are elements and compounds considered to be
  pure substances?

58
Practice Problems

• Why are elements and compounds considered to be
  pure substances?

59
Practice Problems

• Why are elements and compounds considered to be
  pure substances?
• Elements and compounds have a unique set of
  physical and chemical properties.

60
Practice Problems

• Why are both silver and bromine considered pure
  substances even though bromine contains two atoms?

bromine
silver
61
Practice Problems

• Why are both silver and bromine considered pure
  substances even though bromine contains two
  atoms?
• Both silver and bromine are made up of only one
  type of atom.

bromine
silver
62
Practice ProblemsClassify each of the following
as an element or a compound.

• Water

63
Practice ProblemsClassify each of the following
as an element or a compound.

• Water
• Compound

64
Practice ProblemsClassify each of the following
as an element or a compound.

• O2

65
Practice ProblemsClassify each of the following
as an element or a compound.

• O2
• Element

66
Practice ProblemsClassify each of the following
as an element or a compound.

• Iron

67
Practice ProblemsClassify each of the following
as an element or a compound.

• Iron
• Element

68
Practice ProblemsClassify each of the following
as an element or a compound.

• KMnO4

69
Practice ProblemsClassify each of the following
as an element or a compound.

• KMnO4
• Compound

70
Section 5

• The purpose of this section is to distinguish
  between homogeneous and heterogeneous mixtures.
  Heterogeneous mixtures are usually easier to
  separate than homogeneous mixtures. Possible
  separation techniques for homogeneous mixtures
  include distillation, crystallization, and
  chromatography.

71
Learning TargetsSection 5

• I can compare and contrast heterogeneous and
  homogeneous mixtures.
• I can explain techniques used to separate
  mixtures.
• I can classify matter as either a pure substance
  or a mixture.
• I can classify mixtures as either heterogeneous
  or homogeneous.

72
Mixtures

• A blend of two or more pure substances
• Do not have specific compositions
• Can be separated into pure substances by ordinary
  physical means
• 2 types of mixtures
• Heterogeneous
• Homogeneous

73
Heterogeneous Mixtures

• Composition is not uniform throughout
• Contains visibly different parts
• Have different properties in different parts of
  the mixture

74
Homogeneous Mixtures

• Do not contain visibly different parts
• Uniform composition throughout
• Has the same properties throughout the mixture
• AKA solutions

75
Practice ProblemsClassify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Gasoline

76
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Gasoline
• Mixture

77
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Gasoline
• Mixture
• Homogeneous

78
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• A stream with gravel at the bottom

79
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• A stream with gravel at the bottom
• Mixture

80
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• A stream with gravel at the bottom
• Mixture
• Heterogeneous

81
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Air

82
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Air
• Mixture

83
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Air
• Mixture
• Homogeneous

84
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Copper metal

85
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Copper metal
• Pure substance

86
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Copper metal
• Pure substance
• Element

87
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Maple syrup

88
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Maple syrup
• Mixture

89
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Maple syrup
• Mixture
• Homogeneous

90
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• The oxygen and helium in a scuba tank

91
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• The oxygen and helium in a scuba tank
• Mixture

92
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• The oxygen and helium in a scuba tank
• Mixture
• Homogeneous

93
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Common table salt (sodium chloride)

94
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Common table salt (sodium chloride)
• Pure substance

95
Practice Problems Classify each of the following
as a pure substance or a mixture. Further
classify pure substances as elements or compounds
and mixtures as heterogeneous or homogeneous.

• Common table salt (sodium chloride)
• Pure substance
• Compound

96
Separating a Mixture

• Filtration
• Distillation
• Crystallization
• Chromatography

97
Filtration

• Separates solids from liquids
• Used to separate heterogeneous mixtures

98
Distillation

• Takes advantage of differences in boiling points
• The liquid with the lower boiling point changes
  into a gas first
• Also used to separate solid impurities in a liquid

99
Crystallization

• Evaporating a liquid from a solution to leave
  behind a crystal solid
• Used to separate homogeneous mixtures

100
Chromatography

• Separation of a mixture in a mobile phase by
  passing it through a stationary phase
• The particles with a stronger attraction to the
  stationary phase wont travel as far as particles
  with a stronger attraction to the mobile phase

101
Practice Problem

• Explain how you would separate a sugar water
  solution into sugar and water.

102
Practice Problem

• Explain how you would separate a sugar water
  solution into sugar and water.
• Distillation can be used to boil off the water
  and leave the sugar behind. The water will
  condense in the cooling tube and can be collected
  in a separate vessel.
• Crystallization could also be used if only the
  sugar needs to be recovered.

103
Section 1

• The purpose of this section is to investigate the
  concept of energy, including its ability to be
  converted into other forms without being created
  or destroyed. Specific heat and calorimetry will
  also be covered in this section.

104
Learning TargetsSection 1

• I can name three basic forms of energy.
• I can state the law of conservation of energy.
• I can explain the relationship between heat
  capacity and the specific heat of a substance.
• I can explain how a calorimeter is used to
  determine the quantity of heat transferred in a
  chemical reaction.
• I can perform specific heat calculations.

105
Energy

• The capacity to do work or produce heat

106
3 Categories of Energy

• Radiant
• Kinetic
• Potential

107
Radiant Energy

• The energy of electromagnetic waves
• Radiation emitted by a source into the
  environment
• Energy that exists in the absence of matter
• Examples
• Sunlight
• Radio Waves
• Gamma Rays

108
Kinetic Energy

• Energy of motion
• KE ½mv2
• Examples
• Thermal
• Mechanical

109
Potential Energy

• Stored energy
• Energy of position
• Examples
• Electrical
• Chemical

110
Measuring Energy

• calorie (cal)
• The amount of energy needed to raise the
  temperature of 1g of H2O by 1oC
• Common unit of energy
• Calorie (Cal)
• Energy stored in food
• 1 Cal 1000 cal
• 1 Cal 1 kcal
• Joule (J)
• SI unit of energy
• 1 cal 4.184 J

111
Law of Conservation of Energy

• Energy is neither created nor destroyed.
• Energy can be converted from one form to another.
• Energy can be transferred from one object to
  another.
• Does not apply to nuclear energy!

112
Exothermic Reactions

• Release heat
• The temperature of the surroundings increase
• Feel warm

113
Endothermic Reactions

• Absorb heat
• The temperature of the surroundings decrease
• Feel cold

114
Practice Problems

• Burning one liter of natural gas produces 9.46
  kcal of heat energy. Express the energy in
  kilojoules.
• Ans. 39.6 kJ

115
Practice Problems

• Suppose you use 135 cal of energy to perform a
  task. How many joules have you used?
• Ans. 565 J

116
Practice Problems

• The energy content of a small tomato is about 17
  Cal. Convert this measurement to joules.
• Ans. 71,000 J

117
Heat and Temperature

• Heat capacity
• The amount of heat needed to raise the
  temperature of an object by 1oC
• For example, the heat capacity of a cup of water
  at 18oC is the number of joules needed to raise
  the temperature of the water in the cup to 19oC
• Depends on mass and composition of the object

118
Heat and Temperature

• Specific heat (Cp)
• The heat capacity of 1 gram of a substance
• The amount of energy needed to raise the
  temperature of 1 g of a substance by 1oC.
• Water has a very high specific heat
• 4.184 J/(goC)
• Cp q / (m x ?T)
• q heat (lost or gained)
• m mass of sample
• ?T Tf - Ti

119
Heat and Temperature

• A small temperature change does not necessarily
  mean that a small quantity of heat was
  transferred.

• A small temperature change may be produced by a
  very large quantity of heat in an object that has
  a very large heat capacity.

120
Practice Problems

• Determine the specific heat of a material if a 35
  g sample absorbed 96 J as it was heated from
  20.oC to 40.oC
• Ans. 0.14 J/(goC)

121
Practice Problems

• If 980 kJ of energy are added to 6200 g of water
  at 18oC, what will the final temperature of the
  water be?
• Ans. 56oC

122
Practice Problems

• A 4.0 g sample of glass was heated from 274 K to
  314 K, a temperature increase of 40. K, and was
  found to have absorbed 32 J of energy as heat.
  What is the specific heat of this type of glass?
• Ans. 0.20 J/(goC)

123
Practice Problems

• How much energy will the same glass sample gain
  when it is heated from 314 K to 344 K?
• Ans. 24 J

124
Calorimetry

• The study of heat flow and heat measurement
• Calorimetry experiments determine the heats of
  reactions by making accurate measurements of
  temperature changes produced in a calorimeter

125
Calorimetry

• The heat lost in the reaction is the heat gained
  by the surroundings and vice versa
• qsys -qsur

126
Calorimetry

• Recall
• Cp q/(m x ?T)
• Rearranging to solve for q
• q m x Cp x ?T (specific heat equation)

127
Calorimetry

• Since qsys -qsur
• msys x Cp sys x ?Tsys (msur x Cp sur x ?Tsur)

128
Recognizing Calorimetry Problems

• Calorimetry problems are characterized by the
  mixing of two substances at different
  temperatures in a common container (calorimeter).
• Be certain that you set up the problem so that
  the heat transfer equations are equal.
• You may be asked to determine the specific heat
  of one of the substances or the final
  temperature.
• An example of the latter follows. It is the
  harder of the two problems to solve.

129
Practice Problems

• A piece of an unknown metal with mass 23.8 g is
  heated to 100.0oC and dropped into 50.0 cm3 of
  water at 24.0oC. The final temperature of the
  system is 32.5oC. What is the specific heat of
  the metal? Ans. 1.1 J/(goC)

130
Practice Problems

• The color of many ceramic glazes comes from
  cadmium compounds. If a piece of cadmium with
  mass 65.6 g and a temperature of 100.0ºC is
  dropped into 25.0 g of water at 15.0ºC, what will
  be the final temperature of the system? Note
  Specific heat of cadmium is 0.2311 J/goC. Ans.
  30 oC

131
Learning TargetsSection 2

• I can compare and convert between the Fahrenheit,
  Celsius and Kelvin temperature scales
• I can define absolute zero

132
Fahrenheit Scale

• Lowest official temperature recorded in the U.S.
  (Jan. 23, 1971, Prospect Creek, AK) -80oF
• Ice melts 32oF
• Typical room temperature 70oF
• Normal body temperature 98.6oF
• Highest official temperature recorded in the U.S.
  (July 10, 1913, Death Valley, CA) 134oF
• Boiling water 212oF
• Surface of the sun 10,000oF
• Typical oven temperature for baking 325oF

133
Celsius Scale

• Lowest official temperature recorded in the U.S.
  (Jan. 23, 1971, Prospect Creek, AK) -62oC
• Ice melts 0oC
• Typical room temperature 21oC
• Normal body temperature 37oC
• Highest official temperature recorded in the U.S.
  (July 10, 1913, Death Valley, CA) 57oC
• Boiling water 100oC
• Surface of the sun 6000oC
• Typical oven temperature for baking 163oC

134
Kelvin Scale

• SI unit for temperature is kelvin (K)
• Degree symbol is not used
• The kelvin is the same size Celsius degree
• 2K 1K 2oC 1oC
• The difference is the location of the zero point
• Absolute zero the point at which the motion of
  particles of matter ceases (KE 0)
• 0K -273oC

135
Temperature Conversions

• oF 9/5oC 32
• oC 5/9(oF 32)
• K oC 273.15