Question

Acetylene, c2h2, has a standard enthalpy of formation, δh° = 226.7 kj/mol, and a standard entropy change for its formation from its elements, δs° = 58.8 j/k•mol. the standard free energy of formation of acetylene is ________ kj/mol.

Answer 1

ΔG⁰ = ΔH⁰ - T ΔS⁰

ΔG⁰ : Standard free energy of formation of acetylene

ΔH⁰ : Standard enthalpy of formation (226.7 kJ/mol)

ΔS⁰ : Standard entropy change (58.8 J / K. mol)

T : Temperature 25°C = 298 K (room temperature)

ΔG⁰ = 226.7 - (298 x 58.8 x 10⁻³) = 209.2 kJ /mol

Answer 2

Explanation:

The given data is as follows.

     $\Delta H^{o}$ = 226.7 kJ/K mol,      

     $\Delta S^{o}$ = 58.8 J/mol = $58.8 \times 10^{-3} kJ/K mol$

         T = $25^{o}C$ = (25 + 273) K = 298 K

Now, calculate the standard free energy of formation of acetylene ($C_{2}H_{2}$) as follows.

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

                        = 226.7 - kJ/mol - 298 K \times 58.8 \times 10^{-3} kJ/K mol[/tex]

                        = 209.2 kJ/mol

Thus, we can conclude that the standard free energy of formation of acetylene is 209.2 kJ/mol.