2SO2 (g) + O2 (g) = 2SO3 (g)
1、求298K时的△rGmθ
△rHmθ = 2△fHmθ (SO3,g) - 2△fHmθ (SO2,g) - △fHmθ (O2,g)
= - 395.7*2 - (-296.83)*2 - 0
= -197.74 (kJ/mol)
△rSmθ = 2 Smθ (SO3,g) - 2 Smθ (SO2,g) - S mθ (O2,g)
= 2*256.6 - 2*248.1 - 205.03
= -188.03 (J / mol K)
△rGmθ = △rHmθ - T △rSmθ
= -197.74 + 298 * 188.03*10^-3
= -141.7 (kJ/mol)
2、求298K时的 Kθ
△rGmθ = - RT ln Kθ
-141.7 *1000 = - 8.314 * 298 ln Kθ
ln Kθ = 57
3、求1000K时的Kθ
ln (K1θ / K2θ ) = (△rHmθ / R )(1/ T2 - 1/T1)
式中,T2 = 1000K,T1 = 298K,代入上式求出K2θ