The document contains data on the concentration of hydrochloric acid (HCl) and sodium hydroxide (NaOH) used in titration experiments, as well as measurements of pH, hydrogen ion concentration, hydroxide ion concentration, and excess base. The data includes initial HCl concentrations ranging from 400.05 to 545 ml and corresponding NaOH volumes ranging from 0.0033333 to 800 ml used to reach different pH values. Measurements of pH, H+, OH-, and excess base are provided for each titration experiment.