what is the pH?

Question

4469.6 grams of 10% H2SO4 mixed with 1047 grams of 45% KOH and 70 L of water, gives a pH of 1.5, however my calculations give a pH of 2.02, what is going on here?

Answer 1

4469.6g of 10% H2SO4 corresponds to 446.96g of pure H2SO4 mass molar 98 this equals to 446.96/98 =4.56moles of H2SO4
1047g of 45% KOH =471.15 g of KOH . molar mass of KOH=56 so 471.15/56=8.413moles of KOH
as H2SO4 +2 KOH---> K2SO4+ 2H2O
you remark that you need 2KOH for 1 H2SO4
so 8.413moles of KOH
neutralizes 8.413/2=4.21 moles of H2SO4
which do not influence the ph since the salt is neutral
you remain with 4.56-4.21 =0.35 moles of H2SO4 non neutralized
as H2SO4 is bivalent this correspond to a mole of H of 0.7M
in 70L the molarity of H+is 0.7/70 = 0.01 =10^-2

ans as pH = log1/H+ = log 1/10^-2=log 10^2 =2

If you have 2.02 as answer , it can be for precisionbut it is very near