Matter and Energy Chapter 3

1. Matter and EnergyChapter 3

2. Properties • Characteristics of the substance under observation • Properties can be either • directly observable or • the manner something interacts with other substances in the universe

3. Universe Classified • Matter is the part of the universe that has mass and volume • Energy is the part of the universe that has the ability to do work • 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

4. Properties of Matter • Physical Properties are the characteristics of matter that can be changed without changing its composition • Characteristics that are directly observable • Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy • Characteristics that describe the behavior of matter

5. Classify Each of the following as Physical or Chemical Properties • The boiling point of ethyl alcohol is 78°C. • Diamond is very hard. • Sugar ferments to form ethyl alcohol.

6. Classify Each of the following as Physical or Chemical Properties • The boiling point of ethyl alcohol is 78°C. • Physical property – describes inherent characteristic of alcohol – 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 – forming a new substance (ethyl alcohol)

7. States of Matter • solid, liquid, gas

8. Liquid water takes the shape of its container.

9. Changes in Matter • Physical Changes are changes to matter that do not result in a change the fundamental components that make that substance • State Changes – boiling, melting, condensing • Chemical Changes involve a change in the fundamental components of the substance • Produce a new substance • Chemical reaction • Reactants  Products

10. Classify Each of the following as Physical or Chemical Changes • Iron metal is melted. • Iron combines with oxygen to form rust. • Sugar ferments to form ethyl alcohol.

11. Classify Each of the following as Physical or Chemical Changes • Iron 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 react to make a new substance, rust • Sugar ferments to form ethyl alcohol. • Chemical change – describes how sugar forms a new substance (ethyl alcohol)

12. Elements and Compounds • Substances which can not be broken down into simpler substances by chemical reactions are called elements • Most substances are chemical combinations of elements. These are called compounds. • Compounds are made of elements • Compounds can be broken down into elements • Properties of the compound not related to the properties of the elements that compose it • Same chemical composition at all times

13. Classification of Matter • Homogeneous = uniform throughout, appears to be one thing • pure substances • solutions (homogeneous mixtures) • Heterogeneous = non-uniform, contains regions with different properties than other regions

14. Pure Substances vs. Mixtures • Pure Substances • All samples have the same physical and chemical properties • Constant Composition  all samples have the same composition • Homogeneous • Separate into components based on chemical properties • Mixtures • Different samples may show different properties • Variable composition • Homogeneous or Heterogeneous • Separate into components based on physical properties • All mixtures are made of pure substances

15. Identity Each of the following as a Pure Substance, Homogeneous Mixture or Heterogeneous Mixture • Gasoline • A stream with gravel on the bottom • Copper metal

16. Identity Each of the following as a Pure Substance, Homogeneous Mixture or Heterogeneous Mixture • Gasoline • a homogenous mixture • A stream with gravel on the bottom • a heterogeneous mixture • Copper metal • A pure substance (all elements are pure substances)

17. Different Physical Property Technique Boiling Point Distillation State of Matter (solid/liquid/gas) Filtration Adherence to a Surface Chromatography Volatility Evaporation Separation of Mixtures • Separate mixtures based on different physical properties of the components • Physical change

18. Energy and Energy Changes • Capacity to do work • chemical, mechanical, thermal, electrical, radiant, sound, nuclear • Energy may affect matter • e.g. raise its temperature, eventually causing a state change • All physical changes and chemical changes involve energy changes

19. Heat • Heat: a flow of energy due to a temperature difference • Exothermic = A process that results in the evolution of heat. • Example: when a match is struck, it is an exothermic process because energy is produced as heat. • Endothermic = A process that absorbs energy. • Example: melting ice to form liquid water is an endothermic process.

20. Units of Energy • One calorie is the amount of energy needed to raise the temperature of one gram of water by 1°C • kcal = energy needed to raise the temperature of 1000 g of water 1°C • joule • 4.184 J = 1 cal • In nutrition, calories are capitalized • 1 Cal = 1 kcal

21. Example - Converting Calories to Joules Convert 60.1 cal to joules

22. Energy and the Temperature of Matter • The amount the temperature of an object increases depends on the amount of heat added (Q). • If you double the added heat energy the temperature will increase twice as much. • The amount the temperature of an object increases depends on its mass • If you double the mass it will take twice as much heat energy to raise the temperature the same amount.

23. Specific Heat Capacity • Specific Heat (s) is the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree Amount of Heat = Specific Heat x Mass x Temperature Change Q = s x m x T

24. Specific Heat of Water = 4.184 Example – Calculate the amount of heat energy (in joules) needed to raise the temperature of 7.40 g of water from 29.0°C to 46.0°C Mass = 7.40 g Temperature Change = 46.0°C – 29.0°C = 17.0°C Q = s x m x T

25. Table 3.2 lists the specific heat of gold as 0.13 Therefore the metal cannot be pure gold. Example – A 1.6 g sample of metal that appears to be gold requires 5.8 J to raise the temperature from 23°C to 41°C. Is the metal pure gold?