SDN Members don't see this ad. (About Ads) This is a 2 question thread, if you don't mind Question 1: Can someone give me a simple, but thorough D) explanation on how deltaG and Keq are related? The specific example that triggered the question is related to transesterification. Explained here by TBR: "A C-O and a O-H bond were both broken in the reactants and formed in the products. This implies that the enthalpy for the reaction is roughly 0. Going from an ester and non-cyclic alcohol to an ester and non-cyclic alcohol generates a change in entropy of roughly 0, because the reaction starts and finishes with roughly the same degrees of freedom. This implies that the change in free energy for transesterification is around 0. This means the equilibrium constant for transesterification is approximately 1." I understand the reasoning behind deltaH = 0, deltaS = 0 and deltaG=0, but I don't understand how you can determine that Keq is 1. I know that Keq = 1 indicates that there is equilibrium between products and reactants, since Keq is [P]/[R], but just because Gibbs is 0 doesn't mean the reaction is in equilibrium does it? I know that negative delta G means the reaction is spontaneous, but doesn't the activation energy still need to be reached? Meaning, not every reaction with negative deltaG occurs constantly. Question 2: The next line says "Transesterification can be used for shuttles in the cell membrane" Are there any examples of this that we should know for the MCAT?