Chemistry Titration Problem

Question

A student titrates a 20.13 mL sample of HCl of unknown concentration. She begins her titration at the 0.00 mL mark and ends the titration at the 33.98 mL mark. The NaOH solution has a molarity of 1.232. What is the concentration of HCl?

Answer 1

Volume of 1.232 M NaOH = 33.98 ml

moles NaOH used = 33.98 ml x 1 L/1000 ml x 1.232 mol/L = 0.04186 moles NaOH used

Since the reaction is HCl + NaOH ==> NaCl + H2O, there is a 1:1 mol ration of HCl to NaOH. Therefore,

moles HCl = 0.04186 mol

Concentration of HCl = moles/liters = 0.04186 moles/0.02013 L = 2.07965 M = 2.080 M (4 sig. figs.)