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J. W. Hill, R. H. Petrucci, T. W. McCreary, & S. S. Perry General Chemistry 4th edition

Problem 17.53

Use the data from Appendix C to determine Kp at 298 K for these reactions.

(a) 2 SO2(g) + O2(g)2 SO3(g)

(b) CH4(g) + 2 H2O(g)CO2(g) + 4 H2(g)






Answer:

(a) 2 SO2(g) + O2(g)2 SO3(g)

Gfo (SO3(g)) = –371.1 kJ/mol

Gfo (SO2(g)) = –300.2 kJ/mol

Gfo (O2(g)) = 0 kJ/mol

Go = [2(–371.1)] – [2(–300.2) + (0)] = –141.8 kJ

Go = –RTlnKp

–141800 = –(8.314)(298)lnKp

Kp = e57.23 = 7.2×1024


(b) CH4(g) + 2 H2O(g)CO2(g) + 4 H2(g)

Gfo (CO2(g)) = –394.4 kJ/mol

Gfo (H2(g)) = 0 kJ/mol

Gfo (CH4(g)) = –50.75 kJ/mol

Gfo (H2O(g)) = –228.6 kJ/mol

Go = [(–394.4) + 4(0)] – [(–50.75) + 2(–228.6)] = 113.6 kJ

Go = –RTlnKp

113600 = –(8.314)(298)lnKp

Kp = e–45.85 = 1.2×10–20