1. Chapter 3
Matter and Energy

2. Assigned Problems Recommended Exercises: 1-27 (odd) Required
Problems: (odd)
Cumulative Problems: (odd)
Optional
Highlight Problems: (odd)

3. What Is Matter?
Matter is any material that has mass and occupies space
Matter is made up of small particles
Atoms
Molecules
Includes all things (living and nonliving) such as plants, soil, and rocks and any material we use such as water, wood, clothing, etc.
Classifications (of a sample of matter) is based on whether its shape and volume are definite or indefinite
The materials we use

4. Classifying Matter According to Its State
Solid
Has a rigid, definite shape and definite volume
Crystalline solids have a regular, internal long-range order of atoms, ions, or molecules
Amorphous solids have no long-range order of atoms, ions, or molecules in their lattice structure
Liquid
Has an indefinite shape and a definite volume.
It will take the shape of the container it fills
Gas
Has an indefinite shape and an indefinite volume.
It will take the shape and completely fill the volume of the container it fills
Gases are compressible

5. Water is one of the few substances commonly found in all three physical states
Three states of matter

6. Classifying Matter by Its Composition
Matter can also be classified in terms of its chemical composition
Pure Substances: Composed of only one atom or molecule
Mixtures: Composed of two or more different atoms or molecules combined in various proportions

7. Pure Substances
Matter that has a definite and constant composition is a pure substance
Composed of the same substance; no variation
6 million pure substances have been isolated: 112 are elements, the rest are compounds
The two classifications of pure substances:
Elements: e.g., a pure sample of copper or a pure sample of gold (one type of atom)
Compounds: e.g., example, a pure sample of water or a pure sample of sucrose (one type of molecule)

8. Pure Substances Elements
Substances which can not be broken down into simpler substances by chemical reactions
Fundamental substances
Compounds
Two or more elements combined chemically in a definite and constant ratio
Can be broken down into simpler substances
Most of matter is in the compound form
Two types of pure substances

9. Pure Substances Compounds
Results from a chemical combination of two or more elements
Can be broken down into elements by chemical processes
Properties of the compound not related to the properties of the elements that compose it
Water is composed of hydrogen and oxygen gases (combined in a 2:1 ratio)

10. Mixtures Something of variable composition
Result from the physical combination of two or more substances (elements or compounds)
Made up of two or more types of substances physically mixed
Each substance retains its identity because the substances are not chemically mixed
Mixtures of the same components can vary in composition
You can dissolve a small amount of sugar in water and then increase the amount of sugar

11. Mixtures
Mixtures can be classified by the (visual) uniformity of the mixture’s components
Homogeneous mixture:
Same uniform composition throughout
Not possible to see the two substances present
Heterogeneous mixture:
Composition is not uniform throughout the sample.
It contains visibly different parts or phases

12. Mixtures Homogenous mixtures A sugar solution
14 karat gold, a mixture of copper and gold
Air, a mixture of gases (oxygen, nitrogen)
Heterogeneous mixture
Oil and vinegar
Raisin cookies
Sand
Pure substance
e.g. copper (all elements are pure substances)

13. Compounds vs. Mixtures Compounds are not mixtures
Cannot be separated by a physical process
Can be subdivided by a chemical process into two or more simpler substances
Simpler substances have different properties from the compound
Mixtures
Unlike compounds, mixtures can be separated by a physical process
Each substance in a mixture retain its own individual properties

14. Classification of Matter
Physical Methods
Chemical Methods

15. Physical and Chemical Properties
Various kinds of matter are differentiated by their properties
Properties are the characteristics of a substance used to identify and describe it
Two general categories:
Physical Properties
Chemical Properties
Properties can be:
Directly observable (physical)
The interaction of the matter with other substances (chemical)

16. Physical and Chemical Properties: Physical Properties
A physical property is a characteristic of a substance that can be observed without changing a substance into another substance
Characteristics of matter that can be directly observed or measured without changing its identity or composition
Color, odor, physical state, density, melting point, boiling point

17. Physical and Chemical Properties: Chemical Properties
A chemical property describes the way a substance undergoes a change or resists change to form a new substance
Properties that matter exhibits as it undergoes changes in chemical composition:
Objects made from copper will turn green when exposed to moist air for long periods
Gold objects will resist change when exposed to moist air for long periods
Sodium metal will react strongly with water and produce hydrogen gas.

18. Classifying Properties
The boiling point of ethyl alcohol is 78 °C
Physical property – describes an inherent characteristic of alcohol, its boiling point
Diamond is very hard
Physical property – describes inherent characteristic of diamond – hardness
Sugar ferments to form ethyl alcohol
Chemical property – describes behavior of sugar, ability to form a new substance
(ethyl alcohol)

19. Physical and Chemical Changes
Changes in matter are regular occurrences:
Food is cooked
Paper is burned
Iron rusts
Matter undergoes changes as a result of the application of energy
Changes in matter are also categorized as two types:
Physical
Chemical

20. Physical and Chemical Changes
A physical change is a process that alters the appearance of a substance but does not change its chemical identity or composition
Folding aluminum foil sheets
Crushing ice cubes
No new substance is formed
Most common is a change of a substance’s physical state
The freezing of liquid water
Evaporation of liquid water to steam

21. Physical and Chemical Changes
A chemical change is a process that changes the chemical composition of a substance
Also called a chemical reaction
(At least) one new substance is produced
Wood burning, iron rusting, alka-seltzer tablet reacting with water
During a chemical change, the original substance is converted into one or more new substances with different chemical and physical properties

22. Classifying Changes Melting of snow Burning of gasoline
Physical change – a change of state but not a change in composition
Burning of gasoline
Chemical change – combines with oxygen to form new compounds
Rusting of iron
Chemical change – combines with oxygen to form a new reddish-colored substance (ferric oxide)

23. Classifying Changes Iron metal is melted
Physical change – describes a state change, but the material is still iron
Iron combines with oxygen to form rust
Chemical change – describes how iron and oxygen combine to make a new substance, rust (ferric oxide)
Sugar ferments to form ethyl alcohol
Chemical change – describes how sugar forms a new substance (ethyl alcohol)

24. Conservation of Mass
During a physical change: No new substance is formed
During a chemical change: At least one new substance is formed
Whether it is a physical or chemical change, the amount of matter remains the same
The law of conservation of mass states that the total mass of materials present after a chemical reaction is the same as the total mass before the reaction
Matter is never created or destroyed

25. Energy Two major components of the universe:
Matter
Energy
Energy is the capacity to do work or produce heat
Electrical, radiant, mechanical, thermal, chemical, nuclear
Nearly all changes that matter undergoes involves the release or absorption of energy
Chemistry is the study of matter
The properties of different types of matter
The way matter behaves when influenced by other matter and/or energy
Energy can do work or transfer heat

26. Energy
Energy is the part of the universe that has the ability to do work
Energy can be converted from one form to another but it is neither created nor destroyed (the law of conservation of energy)
Energy has two classifications
Potential: Stored energy
Kinetic: Motion energy
All physical changes and chemical changes involve energy changes

27. Energy Potential energy:
Determined by an objects position (or composition)
Chemical energy (also potential energy) is stored in the bonds contained within a molecule. It is released in a chemical reaction
Kinetic energy
Energy that matter acquires due to motion
Converted from the potential energy
All forms of energy can be quantified in the same units

28. Units of Energy The joule (J) is the SI unit of heat energy
The calorie (cal) is an older unit used for measuring heat energy (not an SI unit)
The amount of energy needed to raise the temperature of one gram of water by 1°C
The Cal is the unit of heat energy in nutrition
4.184 J = 1 cal
1 kcal = 1000 cal
1 Cal = 1000 cal = 1 kcal

29. Energy: Chemical and Physical Change
All physical changes and chemical changes involve energy changes which convert energy from one form to another
In terms of a chemical reaction the universe is divided into two parts:
The system (chemical reaction)
The surroundings (everything else)
The potential energy differences between the reactants and products determine whether heat flows into or out of a chemical system
Whether a reaction is exothermic or endothermic depends on how the potential energy of the products compares to the PE of the reactants

30. Energy: Chemical and Physical Change
Chemical systems with high potential energy tend to change in order to lower their potential energy by the release of heat
Chemical reactions that release heat are called exothermic
Chemical systems with low potential energy tend to change in order to increase their potential energy by the absorption of heat
Chemical reactions that absorb heat are called endothermic

31. Temperature
Temperature is a number related to the average kinetic energy of the molecules of a substance
In a substance, the temperature:
measures the hotness or coldness of an object
measures the average molecular motions in a system
relates (directly) to the kinetic energy of the molecules

32. Temperature Fahrenheit Scale, °F Used in USA Celsius Scale, °C
Water’s freezing point = 32°F, boiling point = 212°F
Celsius Scale, °C
Used in science (USA) and everyday use in most of the world
Temperature unit larger than the Fahrenheit
Water’s freezing point = 0°C, boiling point = 100°C

33. Temperature Kelvin Scale, K SI Unit Used in science
Temperature unit same size as Celsius
Water’s freezing point = 273 K (0 ºC), boiling point = 373 K (100 ºC)
Absolute zero is the lowest temperature theoretically possible
No negative temperatures
Differs from the Celcius scale only in numerical values assigned to their reference points

34. Converting °C to °F Units are different sizes
Fahrenheit scale: 180 degree intervals between freezing and boiling
Celsius scale: 100 degree intervals between freezing and boiling

36. Converting °C to °F To convert from °C to °F
Different values for the freezing points
Different size of the degree intervals in each scale
32 °F
0 °C
add 32 to the °F value

37. Converting °C to K Temperature units are the same size
Differ only in the value assigned to their reference points
25°C is room temperature, what is the equivalent temperature on the Kelvin scale?
0 °C =
273 K
K = °C + 273
add 273 to the °C value
25 ºC = 298 K
25 ºC = 298 K
25 ºC = 298 K

38. Example
A cake is baked at 350 °F. What is this in Centigrade/Celsius? In Kelvin?
318 °F

39. Temperature Changes: Heat Capacity
Heat is the total amount of energy in a system
It is function of the amount of motion (kinetic energy) contained in molecules
It is also a function of the potential energy of the molecules
It involves the exchange of thermal energy caused by a temperature difference

40. Heat vs. Temperature Within a quantity of matter:
Heat has units of Joules and temperature has units in degrees
Temperature relates only to kinetic energy within a molecule
Heat is the total amount of energy in a molecule: It contains a kinetic and potential energy component
Heat energy can be added or removed without a change in temperature
As heat energy increases the temperature increases

41. Temperature Changes: Heat Capacity
Heat energy is the form of energy most often released or required for chemical and physical changes
Every substance must absorb a different amount of heat to reach a certain temperature
Different substances respond differently when heat is applied
The amount of heat required to raise the temperature of a given quantity of a substance by 1 ºC is called its heat capacity
Heat capacity applies to a specific physical state

42. Temperature Changes: Specific Heat
If J of heat is applied to:
1 g of water, its temperature is raised by 1 °C
1 g of gold, its temperature is raised by 32 °C
Some substances requires large amounts of heat to change their temperatures, and others require a small amount
The precise amount of heat that is required to cause a given amount of substance (in grams) to have a rise in temperature is called a substance’s “specific heat”

43. Specific Heat
The amount of heat energy (q) needed to raise 1 gram of a substance by 1 °C
Specific to the substance
The higher the specific heat value, the less its temperature will change when it absorbs heat
SH values given in table 3.4, page 71
Only for heating/cooling not for changes in state

44. Specific Heat Expression with Calories and Joules
1 cal is the energy needed to heat 1 g of water 1 °C
1 cal is J
Make a conversion factor from the statements

45. Specific Heat Equation
The rearrangement of the SH equation gives the expression called the “heat equation” C
q = heat
C = specific heat (different for each substance)
m = mass (g)
∆T = change in temperature (°C)

46. Specific Heat Equation
Energy (heat) required to change the temperature of a substance depends on:
The amount of substance being heated (g)
The temperature change (initial T and final T in °C)
The identity of the substance
Identiy of a substance will determine the specific heat value and how much heat it will absorb

47. Energy and T 2× 2×
The amount the temperature of an object increases depends on the amount of heat added (q)
If you double the added heat energy (q), the temperature will increase twice as much.
When a substance absorbs energy, q is positive, temperature increases
When a substance loses energy, q is negative, temperature decreases

48. Energy and Heat Capacity Calculations
Use same problem solving steps as before (Chapter 2)
State the given and needed units
Write the unit plan to convert the given unit to the final unit
State the equalities and the conversion factors
Set up the problem to cancel the units
Pepsi One™ contains 1 Calorie per can. How many joules is this?
State the given and needed units
1 Cal = 1000 cal
4.184 J = 1 cal

49. Energy and Heat Capacity Calculations
The 4184 J from the Pepsi One™ will heat how many grams of water from 0°C to boiling?

50. Energy and Heat Capacity Calculations
How many grams of water would reach boiling if the water started out at room temperature (25°C)?

51. Energy and Heat Capacity Calculations
If 50.0 J of heat is applied to 10.0 g of iron, by how much will the temperature of the iron increase?
Solve for ΔT

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