The standard enthalpy of fusion of iodobenzene is 9.75 kJ/mol at its melting point,241.8 K.What is the standard change in entropy for the melting of iodobenzene at its melting point?
A)0.0189 J/(mol ∙ K)
B)40.3 J/(mol ∙ K)
C)9.75 J/(mol ∙ K)
D)311 J/(mol ∙ K)
E)0.0403 J/(mol ∙ K)

Question

Quizplus · Accepted Answer

The standard molar entropy change for the melting process can be calculated using the following equation:

ΔS = ΔH_fusion / T

where ΔH_fusion is the standard enthalpy of fusion and T is the melting point in Kelvin.

Substituting the values given:

ΔS = 9.75 kJ/mol / 241.8 K = 0.0403 kJ/(mol.K)

To convert the unit to J/(mol.K), we multiply by 1000, giving:

ΔS = 40.3 J/(mol.K)

Therefore, the best choice is B.

The Standard Enthalpy of Fusion of Iodobenzene Is 9