Sodium benzoate, the sodium salt of benzoic acid, is used as a food preservative. A sample containing solid sodium benzoate mixe
d with sodium chloride is dissolved in 50.0 mL of .5 M HCl, giving an acidic solution (benzoic acid mixed with HCl ). This mixture is then titrated with .393 M NaOH. After the addition of 46.50 mL of the solution, the pH is found to be 8.2. At this point, the addition of one more drop ( .02 mL) of NaOH raises the pH to 9.3 . Calculate the mass of sodium benzoate (NaC6H5COO) in the original sample. (Hint: At the equivalence point, the total number of moles of acid [here HCl] equals the total number of moles of base [here, both NaOH and NaC6H5COO]
