Back titration of NaOH with HCl and reason for a back titration
A 40 0 L of N2 gas containing SO2 gas as an impurity was bubbled through a 3% solution of H2O2 The SO2 was converted to H2SO4:
A 25.0 ml portion of 0.0100 mol/l NaOH was added to the solution, and the excess was back-titrated with 13.6 ml of 0.0100 mol/l HCl. Calculate the parts per million of S029that is, ml S02/10 6 ml sample) if the sensity of SO2 is 2.85 g/l ?
I was wondering why do they have to a back-titration?
is it not easier to do a direct titration between H2SO4 and NaOH?