Acetylcholine is a neurotransmitter and its concentration in the blood is quantitatively determined from the pH changes that accompany its hydrolysis by the enzyme, acetylcholinesterase. The products of acetylcholine hydrolysis are choline and acetic acid, which further dissociates to yield acetate and a hydrogen ion. In a typical analysis, 50 mL of an aqueous solution containing an unknown amount of acetylcholine had a pH of 7.6. When incubated with acetylcholinesterase, the pH of the solution is decreased to 6.80. Assuming that there was no buffer in the assay mixture, determine the number of moles of acetylcholine in the 50 mL of the sample. (Assume that the enzyme catalyzed reaction under the given conditions is complete).