REVIEW EXERCISES

General Review

Write a brief and clear answer to each question. Be sure to show your work.

Question 1

1. What have you learned about fire in this unit?

Question 2

2. Generally describe how our energy needs are satisfied by chemical changes.

Question 3

3. Where does the thermal energy from an exothermic reaction come from?

Question 4

4. What do the first and second laws of thermodynamics indicate about energy?

Question 5

5. How many calories of energy are transferred to

  1. raise the temperature of 50 grams of water from 25 ºC to boiling?

  2. lower the temperature of 100 grams of water from boiling to 25 ºC?

Question 6

6. The specific heat capacity of aluminum is 0.21 cal/g ºC. How many calories of thermal energy must be transferred to heat up a 100 g aluminum pot from 20 ºC to 80 ºC?

Question 7

7. For the same number of grams, does it take more or less energy to raise the temperature of aluminum metal or liquid water? Explain.

Question 8

8. The heat of fusion for water is 79.9 cal/g. The heat of fusion for ethanol is 24.9 cal/g. What does this tell you about these two substances?

Question 9

9. Name three ways you can increase the rate of a reaction.

Question 10

10. Define work. How many joules of work are done if a 500 lb piano is lifted by a pulley to a height of 20 m?

Question 11

11. Write and balance the equation for the oxidation of calcium, Ca.

Question 12

12. Write and balance a chemical equation for a redox reaction.

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Question 13

13. Use net ionic equations to show which reactant atoms are oxidized and which atoms are reduced in the following chemical equations.

Zn(s) + 2MnO2(s) → ZnO(s) + Mn2O3(s)

3CaO(s) + 2Al(s) → Al2O3(s) + 3Ca(s)

Question 14

14. Explain how you know which atoms are oxidized and which are reduced in a redox reaction.

Question 15

15. Explain the ray model, the wave model, and the photon model of light. Draw a sketch of each model showing transmission through a thin red plastic film.

Question 16

16. What types of electromagnetic radiation are least harmful? Explain why in terms of wavelength, frequency, and energy.

Question 17

17. Describe the main components of a spectrometer.