Last modified: Wed 12/31/1969 06:00:00 pm
<h3>ACA</h3>

It is OK to use your textbook or lecture notes from class, but if you can answers the questions without it that is OK too.

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Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.


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Here are some questions to see what you have picked up from class on Friday. If you think you need any heat of formation data check out the standard enthalpies of formation table.

1. Which of the diagrams below describe an exothermic process?

Enter your choice.

Briefly explain the reasoning for your choice.

2. Which of the following reactions is exothermic?

A) 2K(s) + 2H2O(l) → 2KOH(g) + H2(g)

B) CCl4(l) → CCl4(g)

C) PCl5(s) → PCl5(l)

D) 2H2O(l) → O2(g) + 2H2(g)

E) O2(g) + N2(g) → 2NO(l)

Enter your choice.

Briefly explain the reasoning for your choice.

3. Write the formation chemical equation for each of the following compounds. NOTE: be sure to include phases for the reactants.

a) K2Cr2O7(s)

b) KHC8H4O4(s)

4. Using the following information calculate the H° for the decomposition of NOCl to its elements?

Chemical Reaction

H° (kJ mol-1)
N2(g) + O2(g) → 2NO(l)

180.6
NO(g) + 1/2Cl2(g) → NOCl(g)

-38.6

H°rxn = kJ mol-1

5. Given the following three reactions, use Hess’ Law to calculate the H°f for OF2(g).

Chemical Reaction

H° (kJ mol-1)
2ClF(g) + O2(g) → Cl2O(g) + OF2(g)

170
2ClF3(g) + 2O2(g) → 3OF2(g) + Cl2O(g)

390
ClF(g) + F2(g) → ClF3(g)

–140

 

H°rxn = kJ mol-1

3. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

4. If there is one question you would like to have answered in lecture, what would that question be?