This document describes an experiment to determine the concentration of an unknown hydrochloric acid solution through acid-base titration with a sodium hydroxide solution of known concentration. The experiment involves performing a coarse titration to identify the approximate range of volumes needed for the endpoint, followed by a precise titration using an indicator to identify the endpoint more accurately. Data such as the volumes, masses, and concentrations are recorded to calculate the molarity of the unknown hydrochloric acid solution.