1. Calculate the change in entropy when 50 kJ of energy is transferred reversibly and isothermally as heat to a large block of copper at (a) 0°C, (b) 70°C.
2. Calculate ΔS (for the system) when the state of 2.00 mol diatomic perfect gas molecules, for which Cp,m = 7/2 R, is changed from 25°C and 1.50 atm to 135°C and 7.00 atm. How do you rationalize the sign of ΔS?
3. A sample consisting of 2.00 mol of diatomic perfect gas molecules at 250 K is compressed reversibly and adiabatically until its temperature reaches 300 K. Given that CV,m = 27.5 J K-1 mol-1, calculate q, w, ΔU, ΔH, and ΔS.
10. The entropy change for a system and its surroundings is greater than zero if the process is:
A) Reversible.
B) Irreversible.
C) Exothermic.
D) Endothermic.
4. The third law of thermodynamics states
A) The entropy of the universe is increasing.
B) The entropy of the universe is constant.
C) The entropy is zero at 0 K for a perfect crystal.
D) The absolute entropy of a substance decreases with increasing temperature.
5. For each of the following processes, the sign of ΔS is negative in
A) The evaporation of alcohol
B) The freezing of water
C) Heating an ideal gas at constant pressure
D) Dissolving NaCl in water
6. The boiling temperature of ethylbenzene is 136°C. Use Trouton's rule to estimate the enthalpy of vaporization of ethylbenzene at this temperature.
A) 35 kJ mol-1
B) 12 kJ mol-1
C) 23 kJ mol-1
D) 4.8 kJ mol-1