Year 12 chemistry): Does pH of a reactant affect the amount of product produced in a chemical reaction?
The answer is no. unless there is a very tiny amount of acid, the limiting factor in the reaction is the magnesium. The number of moles of hydrogen produced will be equal to the number of gram atoms of magnesium and independent of the acid. If there is a very small amount of acid so the acid is the limiting factor then the amount of hydrogen is still independent of the strength of the acid, and therefore the pH. All the available hydrogen in the acid will be used and the equilibrium will shift so as to make all the hydrogen available. So the number of moles of hydrogen will be equal to half the number of gram atoms of hydrogen in the acid.
