Thermodynamics

Topics in this chapter

• Thermodynamic Properties and First Law
• Heat, Work, and Calorimetry
• Enthalpy and Thermochemical Cycles
• Entropy and Second Law
• Gibbs Energy and Equilibrium
• Ideal Gas Thermodynamic Processes

Cheat sheet

Practice questions

1. Question 1Q-B2B791

   For an isolated system, the change in internal energy ($\Delta U$) and change in entropy ($\Delta S$) respectively are:

   1. A.$\Delta U = 0, \Delta S = 0$
   2. B.$\Delta U > 0, \Delta S < 0$
   3. C.$\Delta U = 0, \Delta S > 0$
   4. D.$\Delta U < 0, \Delta S = 0$
   See the answer and solution
2. Question 2Q-646ED5

   Which of the following conditions is always true for a spontaneous reaction at all temperatures?

   1. A.$\Delta H < 0, \Delta S < 0$
   2. B.$\Delta H > 0, \Delta S > 0$
   3. C.$\Delta H < 0, \Delta S > 0$
   4. D.$\Delta H > 0, \Delta S < 0$
   See the answer and solution
3. Question 3Q-1A5DCD

   Calculate the enthalpy of formation of benzene ($\text{C}_6\text{H}_6(\text{l})$) given that the heats of combustion of benzene, carbon, and hydrogen are $-3267\text{ kJ mol}^{-1}$, $-393.5\text{ kJ mol}^{-1}$, and $-285.8\text{ kJ mol}^{-1}$ respectively.

   1. A.+48.5 kJ mol$^{-1}$
   2. B.-48.5 kJ mol$^{-1}$
   3. C.+522.6 kJ mol$^{-1}$
   4. D.-1122.4 kJ mol$^{-1}$
   See the answer and solution
4. Question 4Q-DE7FEB

   During an isothermal reversible expansion of an ideal gas against a constant external pressure, which of the following is correct?

   1. A.$\Delta U = 0, q = -w$
   2. B.$q = 0, \Delta U = w$
   3. C.$w = 0, q = \Delta U$
   4. D.$\Delta S_{\text{universe}} = 0$
   See the answer and solution
5. Question 5Q-DC422A

   The work done in the open vessel at $300\text{ K}$ when $112\text{ g}$ of iron reacts with dilute $\text{HCl}$ is: ($\text{Fe} = 56\text{ g mol}^{-1}, R = 0.0821\text{ L atm K}^{-1}\text{mol}^{-1}$)

   1. A.-1200 cal
   2. B.-2400 cal
   3. C.-300 cal
   4. D.-600 cal
   See the answer and solution