An NaOH(aq) solution cannot be made up to an exact concentration simply by weighing out the required mass of NaOH, because the NaOH is not pure. Also, water vapor condenses on the solid as it is being weighed. The solution must be standardized by titration. For this purpose, a 29.48 mL sample of an NaOH(aq) solution requires 21.26 mL of 0.1085 M HCl. HCl(aq) + NaOH(aq)→ NaCl(aq) + H2O(l) What is the molarity (M) of the NaOH(aq)?