Question

The value of ΔG∘ at 201.0∘C for the formation of phosphorous trichloride from its constituent elements, P2(g)+3Cl2(g)→2PCl3(g) is ________ kJ/mol. At 25.0∘C for this reaction, ΔH∘ is −720.5kJ/mol, ΔG∘ is −642.9kJ/mol, and ΔS∘ is −263.7J/K.

Answer 1

Answer:

The value of ΔG° at 201.0∘C for the formation of phosphorous trichloride is -595.5 kJ/mol.

Explanation:

$P_2(g)+3Cl_2(g)\rightarrow 2PCl_3(g)$

Gibbs free energy of the reaction = ΔG° = -642.9 kJ/mol = -642,900 J/mol

Enthalpy of the reaction = ΔH° = -720.5 kJ/mol = -720,500 J/mol

Change in entropy of the reaction = ΔS° = -263.7 J/mol

Gibbs free energy of the reaction at 201.0°C = ΔG° = ?

T = 201.0°C  = 474.15 K

Using Gibbs's energy equation:

$\Delta G^o=\Delta H^o-T\Delta S^o$

$=-720,500 J/mol- 474.15 K\times (-263.7 J/mol)$

$\Delta G^o=-595,466.64 J/mol=-595.5 kJ/mol$

The value of ΔG° at 201.0∘C for the formation of phosphorous trichloride is -595.5 kJ/mol.