How Do I calculate the pH of water after adding 500 ml of 1 M acetic acid (Ka = 1.8 x10-5) to 500 ml of H2O?

How do I calculate the change in pH, following (i) the addition of 500 ml of 1M Ba(OH)2 to 500 ml of 2O, and (ii) the addition of 500 ml of 1 M acetic acid (Ka = 1.8 x10-5) to 500 ml of H2O.How Do I calculate the pH of water after adding 500 ml of 1 M acetic acid (Ka = 1.8 x10-5) to 500 ml of H2O?
Ka= [H+]^2/[CH3COOH] so [H+]=sqrt([0.5]xKa) then pH=-log[H+]