(1) Citric acid

Dissolve a known volume or weight of sample in a known volume of distilled water. From this, take an aliquot and titrate with 0.1 N NaOH using phenol-phthalein as an indicator. The endpoint is denoted by the appearance of pink colour.

(2) Acetic Acid

Dilute 10 ml of sample with water in a porcelain dish (about 5 inches in diameter), add phenolphthalein as an indicator, and titrate with 0.5 N NaOH.

Calculation

                       Titrate X Normality of alkali X meq wt. of acid* X 100

% Acid   =   ——————————————————————————

                                       Wt. or volume of sample

*Note:   Meq = Millequivlent

Meq wt. of citric acid       = 0.06404

Meq wt. of ascorbic acid = 0.06005