1. (9 pts) Give examples for each of the following:
a) a polar covalent molecule
b) an exothermic reaction
c) an electrolyte
2. (15 pts) Use the table of bond dissociation energies to calculate the heat of reaction for the following:
H2NNH2 + O2 ----> N2 + 2 H2O
Is the reaction exothermic or endothermic?
3. (12 pts) Rank the following fuel sources in terms of their energy content. You must convert the given values to common units in order to make the comparisons.
gasoline - 48 kJ/g
wood - 1300 kcal/lb
cashew nuts - 170 Calories per 30 gram package
4. (12 pts) Explain why sunlight is the ultimate source of energy for the following:
a) wood
b) gasoline
c) hydroelectric power
5. (12 pts) Explain why rain is naturally slightly acidic.
Explain how "acid rain" is caused.
6. Part A (easy) (5 pts)
A beaker contains 100 g of water at 40°C. To this is added 100 g of water at 20°C. After reaching equilibrium, what is the expected final temperature of the water?
Part B (harder) (15 pts)
Consider the following variation on that experiment. A beaker contains 100 g of water at 40°C. To this is added 100 g of aluminum at 20°C. After reaching equilibrium, the observed final temperature of the water is 36°C.
Explain the difference in the two experiments, specifically describing the property of aluminum that is different from water.
Calculate the value of that property, including its proper units.
7. (10pts) Dissolving calcium hydroxide -- Ca(OH)2 -- in water leads to a solution with pH > 7. Is this an acid or a base? Explain by illustrating what happens upon dissolving.
Dissolving phosphorous acid -- P(OH)3 -- in water leads to a solution with pH < 7. Is this an acid or a base? Explain by illustrating what happens upon dissolving.
8. (10 pts) Give your opinion about pollution credits, i.e., the ability of a company to purchase the right to emit a certain amount of pollutants from another company or from the government.