100 ml of 0.1M H3PO4 is titrated with 0.1M NaOH solution calculate ph of solution if voulme of NaOH used is 50 ml Share with your friends Share 4 Geetha answered this The stoichiometric equation is H3PO4 + 3 NaOH -------- Na3PO4 + 3 H2O Since the values are given in Normality, convert molarity into normality Normality = Molarity × Basicity (for acid) Normality = Molarity × Acidity (for base) Given H3PO4 molarity = 0.1 MNormality of H2SO4 = 110 × 3 (since H3PO4 is a tribasic acid) = 310 = 0.3 NNaOH molarity =0.1 M = 0.3 M (since 3 moles are there)Normality of NaOH = 310 × 1 (since NaOH is monobasic) = 310 = 0.3 Nmilli equivalent (meq)= Volume × NormalityFind the meq of acid and base to find the overall solution natureAcid H3PO4 (volume = 100 ml) Base NaOH (volume = 50 ml)100 × 0.3 = 30 50×0.3 = 15Since the acid is having more meq, the resulting solution is acidic.When these two solutions are mixed, the excess is found with acidic solution.i.e., 30 - 15 = 15 meqmeq = Volume × Normality15 = 150 ×Normality (add the two volume for the mixture)Normality = 15150 = 16 NNow calculate pHpH = -log [H+] = - log [110] = -log 10-1 = 1pH of the solution = 1 -3 View Full Answer
