21. Solving a chemistry problem

11. The kinetics of the reversible reaction A↔B was measured at two temperatures. The following experimental data were obtained:
1) T=20 C
t, min 0 10 20 ∞
B content in the mixture% 2.0 21.5 31.0 39.7
2) T=40 C
t, min 0 3 9 ∞
B content in the mixture% 2.0 27.1 45.2 50.7
Calculate:
a) activation energies of direct and reverse reactions;
b) equilibrium constants at two temperatures;
c) thermal effect of direct reaction.