A 10 mL sample of 0.1 M hydrochloric acid is mixed with an equal volume of 0.1 M sodium hydroxide. Write the balanced chemical equation and determine the pH of the resulting solution.

Step-by-step solution

1. Write the balanced equation: $\mathrm{HCl}+\mathrm{NaOH}\to \mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}$
2. Calculate the moles of acid: $0.1,\mathrm{M}\times 0.010,\mathrm{L}=0.001,\mathrm{mol}$
3. Calculate the moles of base: $0.1,\mathrm{M}\times 0.010,\mathrm{L}=0.001,\mathrm{mol}$
4. Since the moles are stoichiometrically equivalent, all acid and base neutralise.
5. The resulting solution contains only $\mathrm{NaCl}$ and water; $\mathrm{NaCl}$ is neutral.
6. The pH of pure water (and hence of this neutral solution) is $7$.

Concept tested: Neutralisation reaction

Published 4 October 2026 · How this solution was prepared and checked