What is the molarity of a hydrochloric acid (HCl) solution if 20.0 mL of 0.0952 M sodium hydroxide (NaOH) is needed to neutralize 10.5 mL of the acid solution?

Answer 1

The balanced equation for this neutralization reaction is

HCl + NaOH ==> NaCl + H2O

moles NaOH used = 20.0 ml x 1 L/1000 ml x 0.0952 mol/L = 0.001904 moles NaOH

moles HCl present = 0.001904 moles HCl (b/c HCl and NaOH react in a 1:1 mole ratio)

Concentration of HCl = moles/L = 0.001904 moles/0.0105 L = 0.181 M (3 significant figures)