dropped into the dilute vinegar solution, ensuring that the solution properly mixed by swirling the vinegar solution after each addition of baking soda. The pH of the vinegar solution was measured using the calibrated Ruolan digital pH meter and recorded along with the volume after the addition of baking soda. The endpoint was determined as the point at which the pH of the vinegar solution made a large incremental increase. After this apparent endpoint, at least five additional increments of baking soda were added to complete the titration curve.