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## PowerPoint Slideshow about ' PRACTICE QUIZ THERMODYNAMICS (20 points) ' - harlan-duncan

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1a. (2 points) DGrxn for:

- 2 SO3(g) 2 SO2(g) + O2(g) is 139.6 kJ.
- If DGf for SO2(g) is -300.1 kJ/mole, calculate DGf for SO3(g)?
- b. (1 point) Is the formation of SO3 gas from SO2 gas and O2 gas spontaneous at 25 ºC and 1 atm pressure?
- c. (1 point) What is the maximum work that could be performed by either of the above reactions?

2. (3 points) Give the expected sign on DS for the following processes:

- Process DS sign
- a. CaSO4(s) CaO(s) + SO3(g) _______
- b. Ag+(aq) + Cl-(aq) AgCl(s) _______
- c. I2(g) I2(s) _______
- 3. (2 points) Circle T (True) or F (False):
- T F a. Endothermic reactions which become more ordered are never spontaneous.
- T F b. A system at equilibrium cannot perform any work.

4. (2 points) For the reaction:

- 5 Fe3++ Mn2++ 4 H2O MnO4-+8 H+ + 5 Fe2+
- Kc = 1.0 x 10-62 Given DG = -2.3 RT log Kc, what is the sign of DG for this reaction?
- 5. (2 points) 1.0 mole of SO2(g) and 1.0 mole of O2(g) are mixed together in a 1.0 L flask. As SO2 and O2 react to form SO3 and proceed toward equilibrium, how does the value of the free energy change?

6. (3 points) The process:

- benzene(s) benzene(l)
- is spontaneous at temperatures above 5 ºC and is spontaneous in the opposite direction at temperatures below 5 ºC.
- a. Explain in terms of DH, DS, and DG why the direction of the spontaneous process depends on the temperature.
- b. What does the temperature 5 ºC represent for benzene?
- c. What is DG for the above process at 5 ºC?

7. (4 points) For the reaction:

- 3 NO2(g) + H2O(l) 2 HNO3(l) + NO(g)
- the following information is given at 25oC and 1 atm:
- DGrxn = + 8.4 kJ
- DHf (kJ/mole):
- + 34.0 for NO2(g);
- -286.9 for H2O(l);
- -173.9 for HNO3(l);
- + 90.7 for NO(g)
- Calculate DS for the reaction (DSrxn)?

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