1. Problems p.94 #32, 36, 38, 43, 45, 46, 49

2. 32. Is carbon dioxide gas a pure substance? Explain. Pure substance; constant composition

3. 36. List 3 states of matter, and give an example for each state. Differentiate between a gas and vapor. 1. SolidEx. Ice 2. LiquidEx. Water 3. GasEx. Helium Substances that are in the gas phase at room temperature are referred to as gases, whereas substances such as water vapor that are not gases at room temperature are vapors.

4. 38. Classify each as physical property or a chemical property. A. Al has a silvery color B. Au has a density of 19 g/cm 3 C. Na ignites when dropped in water D. Water boils at 100 o C E. Ag tarnishes F. Hg is a liquid at room temp A. physical B. physical C. chemical D. physical E. chemical F. physical

5. 43. Classify each as a physical change or a chemical change. A. breaking a pencil in two B. water freezing and forming ice C. frying an egg D. burning wood E. leaves changing colors in the fall chemical physical chemical physical

6. 45. Is a change in phase a physical change or a chemical change? Explain. It is a physical change. The composition of the substance does not change.

7. 46. List 4 indicators that a chemical change has probably occurred. 1. Change in color 2. Change in temperature 3. Production of a gas upon mixing 4. Production of a solid upon mixing

8. 49. Describe the difference between a physical change and a chemical change. A physical change alters a substance without changing its composition, while a chemical change involves a change in composition.