lemon juice has a ph of about 2.5. Assuming that the acidity of lemon juice is due solely to citric acid, that citric acid is a monoprotic acid, and that the density of lemon juice is 1.0g/ml, then the citric acid concentration calculates to 0.5% by mass. estimate the volume of 0.0100M NaOH required to neutralize a 3.71g sample of lemon juice. the molar mass of citric acid is 190.12 g/mol.