A reaction has a standard free energy change of -18.50 kJ/mol. Calculate the equilibrium constant for the reaction at 25C.

I am using the equation deltaG= -2.3RTlog(Keq) with R and G in Joules and T in Kelvin, yet I cannot seem to get the correct answer. Any thoughts on what I might be doing wrong?

Question

A reaction has a standard free energy change of -18.50 kJ/mol.  Calculate the equilibrium constant for the reaction at 25C.  

I am using the equation deltaG= -2.3RTlog(Keq) with R and G in Joules and T in Kelvin, yet I cannot seem to get the correct answer.  Any thoughts on what I might be doing wrong?

anonymous · Answer

The equation is normaly just $$\Delta{G_{Rxn}}= -RTlnK $$make sure you are using the right R(8.314J/mol K) and the right temp(298K). Also it should be natural log not normal base ten log. So ln instead of log. Also make sure that you convert your G to joules since that's what your R is in or vice versa, just make sure they are both in the same units. so it will look like this$$\LARGE e^{\frac{\Delta{G_{Rxn}}}{-RT}}=K_{eq}$$let me know if you don't understand how I got there.