Chapter 2 Homework Answers Chemistry

Energy/Temperature Energy is the capacity to do work or produce heat. Sunlight is an example of radiant energy. Fossil fuels are an example of potential energy. The SI unit of energy is the Joule. The law of conservation of energy states that in any process, energy is neither created nor destroyed. Temperature is a measure of thermal energy. Kinetic energy is the energy of motion.

Energy/Temperature

2-3 Review & Reinforcement Matter is anything that has mass and volume. The two states of matter that occupy a definite volume are liquid and solid. Gas and plasma are the other two states of matter. Chemical changes alter the identity of the substance, whereas physical changes do not.

2-4 Review & Reinforcement

2-4 Review & Reinforcement Elements cannot be separated by physical or chemical means. Elements are abbreviated with symbols, which consist of one or two letters. Elements are organized on the periodic table. Two or more elements chemically combined make up a compound. Carbon is an example of an element and carbon dioxide is an example of a compound. Elements and compounds are called pure substances because they have a unique set of chemical and physical properties.

2-4 Review & Reinforcement

2-5 Review and Reinforcement Heterogeneous 1. alphabet soup Pure – compound 2. salt Heterogeneous 3. concrete Homogeneous 4. vegetable oil Homogeneous 5. air Heterogeneous 7. sea water (if you can see the sand & stuff in it!) Heterogeneous 8. granite Homogeneous 9. steel Pure – compound 10. sugar

2-5 Review and Reinforcement 11. Heterogeneous mixtures are often separated by filtration. 12. Separating sand from water can be done by filtration. 13. The sugar in sugar water can be removed by crystallization. 14. The separation technique that takes advantage of different boiling points is called distillation. 15. Removing chlorophyll pigment from leaves might be done by chromatography. 17. Crude oil is broken down by heat, vaporized and allowed to condense into various liquids. This process is called distillation.

2-5 Review and Reinforcement

Chapter 2 Review 1. Identify the type of energy contained in: A baseball that has just been thrown Kinetic A book hanging on the edge of a shelf Potential Light coming from a lightbulb Radiant

Chapter 2 Review

Chapter 2 Review 3. Solid – definite shape ; definite volume Tightly knit particles with very high relative density Liquid – no definite shape ; definite volume Particles starting to spread out; high density Gas – no definite shape ; no definite volume Particles very far apart; low density

Chapter 2 Review 4.Identify the following as physical or chemical changes: a. Tearing a piece of paper - physical b. A plant converting sunlight into food - chemical c. Burning wood in a fireplace - chemical d. Melting snow - physical e. Baking a cake - chemical f. Crushing rock - physical

Chapter 2 Review 5. 6. a. Ca - Calcium a. Sugar – compound (pure) b. Fluorine - F c. W - Tungsten d. Iron - Fe e. Al - Aluminum f. Sodium - Na 6. a. Sugar – compound (pure) b. Gold – element (pure) c. Tap Water – homo. (other crap in it besides water!) d. Cough syrup – homo? e. Aluminum- element (pure) f. Table Salt – compound (pure)

Chapter 2 Review 7. a. Water & Vinegar (they mix) – Distillation b. Broth & Noodles – Decanting or filtering c. Vinegar & Oil (don’t mix) – Decanting d. Dye – Chromatography e. Sugar & Water - Christallization