In a typical analysis, 15 ml of an aqueous solution containing an unknown amount of acetylcholine had a ph of 7.65. when incubated with acetylcholinesterase, the ph of the solution decreased to 6.87. assuming there was no buffer in the assay mixture, determine the number of moles of acetylcholine in the 15 ml sample.

pH of the solution before incubation = 7.65

pH after the solution was incubated with acetylcholinesterase = 6.87

After incubation,

Difference in the concentration of hydronium ion =

When solution containing acetylcholine is incubated with acetylcholinesterase, acetylcholine is converted to acetic acid and choline. So the decrease in the concentration of acetylcholine will be equal to the increase in the concentration of hydronium ion produced from acetic acid.

Moles of acetylcholine =

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.