The document contains data on the concentration of hydrochloric acid (HCl) and sodium hydroxide (NaOH) used in titration experiments, along with measurements of pH, hydrogen ion concentration, hydroxide ion concentration, and excess base. As more NaOH is added, the pH increases while the hydrogen and hydroxide ion concentrations decrease. The table shows how the measured values change with increasing volumes of NaOH titrated into solutions containing a constant amount of HCl.