Question

Calculate the equilibrium constant, K for the following reaction at 400 K ?
`2NOCl(g) hArr 2NO(g) + Cl_(2)(g)`
Given that ` Delta_(r) H^(@) = 80.0 kJ mol^(_1)` and `Delta_(r)S^(@) =120 J K^(-1) mol^(-1)` at 400 K.

Answer 1

`Delta_(r) G^(@) = Delta_(r)H^(@) - TDelta_(r)S^(@) = 80000J - 400 xx 120 J = 32000 J`
Now, `Delta_(r) G^(@) = -2.303 RT log K `
`:. 32000 = - 2.303 xx 8.314 xx 400 xx logK ` or ` log K = - 4.1782 = bar(5).8218`
`:. K = ` Antilog `bar(5).8218 = 6.634 xx 10^(-5)`