Final answer:
The relationship between molarity and normality for a weak acid with two equivalence points in a titration is that the normality is twice the molarity since it is a diprotic acid, capable of donating two protons per molecule.
Step-by-step explanation:
The titration of a weak acid showing two equivalence points suggests it is a diprotic acid, meaning it can donate two protons (H+) per molecule. Normality (N) is a measure of the equivalent concentration of a solution where one equivalent is the amount of substance that will react with or supply one mole of hydrogen ions (H+) in an acid-base reaction. Since this weak acid has two acidic protons, its normality will be twice its molarity (M) because each mole of acid reacts with two moles of NaOH.
For example, if the molarity of the acid is 0.1 M, its normality would be 0.2 N, because one liter of this acid solution could neutralize twice the amount of NaOH compared to a monoprotic acid at the same concentration. Therefore, the relationship between normality and molarity for this acid is normality equals molarity times the number of acidic protons per molecule of the weak acid.