Thermodynamics · Question 44

Standard entropies of X2, Y2 and XY3 are 60, 40 and 50 J K-1 mol-1 respectively. For the reaction 12X2 + 32Y2 XY3, H = -30 kJ, to be at equilibrium, the temperature should be

1. 750 K
2. 1000 K
3. 1250 K
4. 500 K

The values of and for the reaction, C(graphite) + CO2(g) 2CO(g) are 170 kJ and 170 J K-1, respectively. This reaction will be spontaneous at

1. 910 K
2. 1110 K
3. 510 K
4. 710 K

From the following bond energies : H – H bond energy : 431.37 kJ mol-1 C = C bond energy : 606.10 kJ mol-1 C – C bond energy : 336.49 kJ mol-1 C – H bond energy : 410.50 kJ mol-1 Enthalpy for the reaction, [figure] will be

1. -243.6 kJ mol-1
2. -120.0 kJ mol-1
3. 553.0 kJ mol-1
4. 1523.6 kJ mol-1

Bond dissociation enthalpies of H2, Cl2 and HCl are 434, 242 and 431 kJ mol-1 respectively. Enthalpy of formation of HCl is

1. -93 kJ mol-1
2. 245 kJ mol-1
3. 93 kJ mol-1
4. -245 kJ mol-1

For the gas phase reaction, PCl5(g) PCl3(g) + Cl2(g) which of the following conditions are correct?

1. < 0 and < 0
2. > 0 and < 0
3. = 0 and < 0
4. > 0 and > 0

Which of the following are not state functions? (I) q + w (II) q (III) w (IV) H - TS

1. (I), (II) and (III)
2. (II) and (III)
3. (I) and (IV)
4. (II), (III) and (IV)

Consider the following reactions: (i) H+(aq) + OH-(aq) H2O(l), H = -X1 kJ mol-1 (ii) H2(g) + 12O2(g) H2O(l), H = -X2 kJ mol-1 (iii) CO2(g) + H2(g) CO(g) + H2O(l), H = -X3 kJ mol-1 (iv) C2H2(g) + 52O2(g) 2CO2(g) + H2O(l), H = +X4 kJ mol-1 Enthalpy of formation of H2O(l) is

1. +X3 kJ mol-1
2. -X4 kJ mol-1
3. +X1 kJ mol-1
4. -X2 kJ mol-1

Given that bond energies of H-H and Cl-Cl are 430 kJ mol-1 and 240 kJ mol-1 respectively and Hf for HCl is -90 kJ mol-1, bond enthalpy of HCl is

1. 380 kJ mol-1
2. 425 kJ mol-1
3. 245 kJ mol-1
4. 290 kJ mol-1

Identify the correct statement for change of Gibbs energy for a system ( Gsystem) at constant temperature and pressure.

1. If Gsystem < 0, the process is not spontaneous.
2. If Gsystem > 0, the process is spontaneous.
3. If Gsystem = 0, the system has attained equilibrium.
4. If Gsystem = 0, the system is still moving in a particular direction.

Assume each reaction is carried out in an open container. For which reaction will H = E?

1. 2CO(g) + O2(g) 2CO2(g)
2. H2(g) + Br2(g) 2HBr(g)
3. C(s) + 2H2O(g) 2H2(g) + CO2(g)
4. PCl5(g) PCl3(g) + Cl2(g)