Question

Which is the correct relationship between $\Delta G$ and equilibrium constant $K_p$?

• A. $K_p=-RTlog\Delta G^0$
• B. $K_p=-[e/RT{]}^{\Delta G^0}$
• C. $K_p=-\Delta G^0/RT$
• D. $K_p=e^{-\Delta G^0/RT}$

Answer 1

The correct option is D $K_p=e^{-\Delta G^0/RT}$

For any reaction that is taking place, the change in Gibbs free energy is related to the reaction quotient as;

$\Delta G=\Delta G^0+RT\ln Q$

where,

R-Universal gas constant

T-Temperature in kelvin

Q- Reaction quotient

Now the equilibrium constant is nothing but the reaction quotient of a system

at equilibrium. $\Delta G^0$ is the standard Gibb's free energy, which is defined as,

$\Delta G^0=-RT\ln Kp$

where $K_p$ is the equlibrium constant

This can also be written as

$K_p=e^{-\Delta G^0/RT}$