In each trial, a titration curve was generated by graphing the pH of the vinegar solution against the total volume of baking soda added. The true endpoint of the titration was determined graphically by plotting the second derivative of the function of pH versus volume of sodium bicarbonate added using Logger Pro (). The point at which the graph of the second derivative crossed the x-axis during a recognizable spike pattern was determined to be the volume of sodium bicarbonate added at the equivalence point. The average value of the three trials was calculated and reported as the mean +/-the standard deviation. Using this average endpoint, the concentration of acetic acid in the original vinegar solution was calculated and compared to the advertised 6% acidity composition and the percent error was computed using Eq. 4-7.