Looking at a reaction equation for an esterification reaction you cannot tell where the oxygen comes from (acid or alcohol). Can you devise an experiment using O^18 to prove unequivocally where the Oxygen comes from? What would it be?

Looking at a reaction equation for an esterification reaction you cannot tell where the oxygen comes from (acid or alcohol). Can you devise an experiment using O^18 to prove unequivocally where the Oxygen comes from? What would it be?