Percent Acetic Acid in Vinegar

For the last few days, my lab partner and I have been carrying out the percent acetic acid and vinegar lab, where we titrate acids in order to ultimately find the percent of acetic acid in commercial vinegar. First, we mixed about .5 grams of hydrogen phthalate into water to dilute it. Then, we added an indicator and titrated it with sodium hydroxide until the solution turned pink. When the solution turned pink, we knew that all of the KHP had been reacted with since the NaOH will react with the acid before the indicator. Next, we titrated diluted vinegar with the NaOH until it turned pink too (from the indicator). Since we recorded the amount of solutions used, we can calculate the molarity of the NaOH and find the molarity of the vinegar used. This information will eventually lead us into finding the vinegar's % of acetic acid in it. Here are some pictures from the lab: