Gibbs Free Energy (Simplified) Practice Problems

At 25°C, the ΔG of the following reaction is −1169.2 kJ/mol.

Th(s) + O₂(g) → ThO₂(s)

Determine if the reaction is spontaneous at 25°C.

Consider the following reaction:

2 Sn(s) + O₂(g) → 2 SnO(s), ΔH = −561.42 kJ/mol (−134.18 kcal/mol)

Is the reaction spontaneous at all temperatures?

The reaction Z(s) → X(g) + Y(g) is depicted in the following figure.

Assuming the reaction has ΔH = 52.4 kJ/mol (12.5 kcal/mol), will the reaction be spontaneous at high temperatures?

Identify the true statement from the following statements on factor/s affecting the spontaneity of a reaction.

Plotted on the energy diagram below are blue and orange curves. Identify the curve that represents a nonspontaneous reaction and a spontaneous reaction. 

The reaction X(s) → Y(g) + Z(g) is illustrated in the following figure.

If the reaction has ΔH = 43.2 kJ/mol (10.3 kcal/mol), determine the sign of its ΔS.

Based on the Gibbs free energy equation (ΔG = ΔH − TΔS), which of the following correctly explains when a reaction might be endothermic but exergonic?

Consider the following reaction:

(C₂H₅)₂O(l) ⇌ (C₂H₅)₂O(g)

The ΔH and ΔS for the reaction above are 26.5 kJ/mol (6.34 kcal/mol) and 86.1 J/mol•K (20.6 cal/mol•K), respectively. Determine the values of ΔH (in kJ/mol and kcal/mol) and ΔS (in J/mol•K and cal/mol•K) for the following reaction:

(C₂H₅)₂O(g) ⇌ (C₂H₅)₂O(l)

Choose the true statement from the following statements differentiating an exergonic reaction from an exothermic reaction.

Consider the following reaction:

NH₃(l) ⇌ NH₃(g)

The ΔH and ΔS for the reaction above are 23.3 kJ/mol (5.57 kcal/mol) and 97.3 J/mol•K (23.2 cal/mol•K), respectively. Is the reaction favored or unfavored by ΔH? By ΔS?