General Review
Write a brief and clear answer to each question. Be sure to show your work.
1. What have you learned about fire in this unit?
2. Generally describe how our energy needs are satisfied by chemical changes.
3. Where does the thermal energy from an exothermic reaction come from?
4. What do the first and second laws of thermodynamics indicate about energy?
5. How many calories of energy are transferred to
raise the temperature of 50 grams of water from 25 ºC to boiling?
lower the temperature of 100 grams of water from boiling to 25 ºC?
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?
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.
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?
9. Name three ways you can increase the rate of a reaction.
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?
11. Write and balance the equation for the oxidation of calcium, Ca.
12. Write and balance a chemical equation for a redox reaction.
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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)
14. Explain how you know which atoms are oxidized and which are reduced in a redox reaction.
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.
16. What types of electromagnetic radiation are least harmful? Explain why in terms of wavelength, frequency, and energy.
17. Describe the main components of a spectrometer.