Question

Calculate S* rxn for the following reaction. The S* for each species is shown below the reaction.

C2H₂(g) + 2 H₂ (g) --------------> C₂H₆(g)
S*(J/mol x K) for C₂H₂(g) = 200.9 , for 2H₂ = 130.7, and for C₂H₆ = 229.2

Answer 1

The standard entropy change (ΔS°) for the reaction C2H2(g) + 2 H2(g) → C2H6(g) is calculated using the standard molar entropies of the reactants and products. The ΔS° is -102.4 J/mol·K.

Step-by-step explanation:

The student has asked to calculate the standard entropy change (ΔS°) for a chemical reaction using the provided standard molar entropies (S°) of reactants and products. To calculate ΔS°, we use the formula:

ΔS° = ΣS°(products) - ΣS°(reactants)

For the reaction C2H2(g) + 2 H2 (g) → C2H6(g), the S° values are:

• S° for C2H2(g) = 200.9 J/mol·K
• S° for 2H2 = 130.7 J/mol·K (for two moles)
• S° for C2H6 = 229.2 J/mol·K

Substituting these values into the formula gives:

ΔS° = (229.2) - (200.9 + 130.7)

ΔS° = 229.2 - 331.6 = -102.4 J/mol·K

Therefore, the standard entropy change for the reaction is -102.4 J/mol·K.