Gibbs Energy Change

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

The enthalpy and entropy change for the reaction: Br₂ (l) + Cl₂ (g) →2BrCl(g), are 30kJ mol^-1 and 105 JK^-1 mol^-1 respectively. The temperature at which the reaction will be in equilibrium is:

1. 285.7 K

2. 273 K

3. 450 K

4. 300 K

The values of ΔH and ΔS for the given reaction are 170 kJ and 170 JK^-1, respectively.
C_(graphite) + CO₂(g)→2CO(g)
This reaction will be spontaneous at:

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

Standard entropies of X₂, Y₂ and XY₃ are 60, 40 and 50JK^-1mol^-1 respectively. For the reaction
$\frac{1}{2}{\mathrm{X}}_2$ $+$ $\frac{3}{2}{\mathrm{Y}}_2$ $$ $\leftrightharpoons$ ${\mathrm{XY}}_3$ $;$ $∆\mathrm{H}$ $=$ $-30$ $\mathrm{kJ}$ to be at equilibrium, the temperature should be:

1. 750 K

2. 1000 K

3. 1250 K

4. 500 K

In which of the following reactions, the standard reaction entropy change
$(∆S^0)$ is positive, and standard Gibb's energy change
$(∆G^0)$ decreases sharply with increasing temperature?

For a given reaction, ∆H = 35.5 kJ mol^–1 and ∆S = 83.6 J K^–1 mol^–1. The reaction is spontaneous at:
[Note: Assume that ∆H and ∆S do not vary with temperature]

1. T > 425K
2. All temperatures
3. T > 298K
4. T < 425K

A process among the following shows decrease in entropy is :

1.

2. Evaporation of water

3. Expansion of a gas at a constant temperature

4. Sublimation of solid to gas