Question

You and your lab partner are doing a "blind" analysis of two beverage samples; that is, you don't know what the source of the samples are. You determine that the pH of both samples is 3.55. One unknown sample takes an average of 8.7 ml of 0.1 N KOH to titrate to pH 7.0; the other unknown sample takes an average of 8.5 ml to reach pH 7.0. Your partner believes that because the two volumes of titrant needed are within experimental error (based on statistical anaylsis), the concentration of predominant acid is the same in both samples. Do you agree or disagree? Explain your answer. FYI, the titratable acidity equation is %acid = [(N x V x Eq. Wt.) / (sample wt. x 1000)] x 100 where N is normality of titrant, V is volume of titrant, Eq. Wt. is equivalent weight of the predominant acid.

Answer 1