As a result of studying changes in matter and how they occur:

Students understand the differences between physical and chemical changes in matter.

• Describe the physical states of matter (solids, liquids and gases) in terms of the arrangement and motion of particles, and explain how heat is related to changes in the physical state of matter. (PIIA1)

1. A child releases a balloon that is partially inflated with helium into the air. What do you think will happen to the size of the balloon as it rises? Explain fully why you think so.

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2. Which of the following graphs shows how the rate of evaporation changes with changes in water temperature?

3. During which of the following processes is there a decrease in the heat content of the form of water indicated?

a. Ice as it forms on a lake
b. Water droplets as they fall to the ground
c. Water as it evaporates from a pond
d. Snow as it melts on a mountainside

4. As water boils, the arrangement and behavior of the water molecules undergo changes.   Describe at least two of these changes.

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5. When very small particles in a dish of water are examined with a powerful microscope, the particles often appear to move in a rapid, random motion. Explain what causes this movement of the particles.

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• Describe the differences between chemical and physical changes in matter and explain how chemical changes involve the rearrangement of molecules, atoms or ions to form new substances. (PIIA2)

6. Which method is the most effective in removing a salt from a solution of water?

A. Pour the water from the solution.
B. Use a magnet to attract the salt.
C. Allow the water to evaporate.
D. Pour the solution through a filter paper.

7. In a beaker, sugar is dissolved in water, and then the water is heated and evaporates. The sugar is recovered, and heat is again applied. Vapor is released, and the material in the beaker changes from white to black. What must you know to determine if a chemical change occurred?

a. the boiling point of water
b. the boiling point of sugar
c. the temperature at which sugar evaporates
d. whether or not the black substance is sugar

Students understand that materials interact with each other in various forms.

• Explain that the total matter and energy are conserved in synthesis and decomposition reactions. (PIIB1)

8. In an experiment, 12.0 grams of solid carbon reacted with oxygen gas to form 44.0 grams of carbon dioxide gas. How many grams of oxygen reacted with the carbon?

a. 12.0 grams
b. 32.0 grams
c. 44.0 grams
d. 56.0 grams

9. A balanced chemical equation reflects the idea that the mass of the products

a. is greater than the mass of the reactants.
b. is less than the mass of the reactants.
c. equals the mass of the reactants.
d. is not related to the mass of the reactants.

• Describe combustion and corrosion reactions of materials with oxygen (i.e., burning, respiration and rusting). (PIIB2)

10. When steel wool rusts, the iron in the steel wool combines with

a. nitrogen
b. carbon dioxide
c. oxygen
d. hydrogen

11. Which of the following statements best describes the energy transformation that occurs when a log burns?

a. Mechanical energy changes to chemical energy.
b. Chemical energy changes to heat and light energy.
c. Heat and light energy changes to chemical energy.
d. Mechanical energy changes to heat and light energy.

12. A log was burned in a fireplace. Which statement is true about the leftover ashes when they are compared to the original unburned log?

a. The ashes have more mechanical energy than the unburned log.
b. The ashes occupy the same amount of space as the unburned log.
c. The ashes have less chemical energy than the unburned log.
d. The ashes have the same molecular structure as the unburned log.

13. Which of the following equations best represents the burning of a log?

a. Wood + CO₂    O₂ + H₂O + energy
b. Wood + O₂   CO₂ + H₂O + energy
c. Wood + H₂O    O₂ + CO₂ + energy
d. Wood    CO₂ + O₂ + H₂O + energy

• Describe the chemical structures and properties of acids and bases and relate them to the properties of common household products. (PIIB3)

14. Natasha is concerned about acid rain. A snow sample has a pH of 6.5. Natasha proposes explanations for the observed pH. Which explanation is most reasonable?

a. The slightly basic pH represents clean air.
b. The slightly acidic pH represents clean air.
c. The acidic pH indicates that a pollution source must be upwind.
d. The basic pH indicates that a pollution source must be upwind.