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1. The melting point of water is 0oC at 1 atm pressure because under these conditions:
DS for the process H2O(s)--> H2O(l) is positive.
DS and DSsurr for the process H2O(s)--> H2O(l) are both positive.
DS and DSsurr for the process H2O(s)--> H2O(l) are equal in magnitude and opposite in sign.
DG is positive for the process H2O(s)--> H2O(l).
None of these is correct.

2. For the dissociation reaction of the acid HF: HF<-->H++ F -
DS is observed to be negative. The BEST explanation for this is:

This is the expected result since each HF molecule produces two ions when it dissassociates
Hydration of the ions produces the negative value of DS.
The reation is expected to be exothermic and thus D should be negative.
The reaction is expected to be endothermic and thus D should be negative.
None of these can explain the negative value of DS.

3. Which of the following will be true when a pure substance in liquid phase freezes spontaneously?
DG, DH, and DS are all positive
DG, DH, and DS are all positive

4. Rubidium has a heat of vaporization of 69.0 kJ/mol at its boiling point (686oC). For the process Rb(l)-->Rb(g) at 1 atm and 686oC. Calculate the value of DS.
0
69.0 kJ/mol
71.9 J/K mol
61.0 kJ/mol
-7.97 kJ/mol

5. Which of the following favors a negative DG?
increasing energy and increasing entropy
lowering energy and increasing entropy
increasing energy and decreasing entropy
lowering energy and decreasing entropy
none of the above

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