For the reaction A (aq) ---> B (aq) the change in the standard free energy is 2.60 kJ at 25°C and 4.98 at 45 °C. Calculate the value of the equilibrium constant for this reaction at 75 °C.

First I used Gibbs free energy equation  to find k1 and k2

Second, I used Van Toff eqaution tofind variation H

step 3 : from definition of gibbs energy for 25° I found Variation S

step 4: for T=75°C I found ?G using formula 

step5: I calculated k value @T=75°C by isolating k in the equation : 

Still I got wrong answer k=0.05

 

 

AG-RT In Keq