What is the pH?

Question

A 200.0 mL sample of 0.40 M Ba(OH)₂ is titrated with 0.40 M HBr. Determine the pH of the solution after the addition of 400.0 mL HBr.

Answer 1

2HBr + Ba(OH)₂ ==> 2H₂O + BaBr₂ ... balanced equation

Total volume = 200.0 ml + 400.0 ml = 600.0 ml = 0.6000 L

mols HBr = 0.4 L x 0.40 mol/L = 0.16 mols HBr

mols Ba(OH)₂ = 0.200 L x 0.40 mol/L = 0.08 mols Ba(OH)₂

Since the mol ratio of HBr to Ba(OH)2 is 1:2, this titration is @ equivalence.

Since this is a titration of a strong base with a strong acid, the pH @ equivalence = 7