How Do You Calculate pH After Titration of HOBr with NaOH?

[gerry73191]

Homework Statement

20.0 mL of a 0.1 M solution of sodium hydroxide is titrated into 50.0 ml of the 0.14 M HOBr solution. Calculate the pH of the resulting solution.

ph of HOBr is 4.74

Ka is 2.3e-9

Homework Equations

[H+] = ka(a/b)

-log[h+] = ph

ka*kb=kw

The Attempt at a Solution

honestly i have no clue how to do this problem. I already know the answer its 8.24, but I haven't a clue how to get it. can someone point me in the right direction?

thanks

 

[Borek]

Calculate concentrations of HOBr and OBr^- (just from the neutralization reaction stoichiometry), plug these numbers in the Henderson-Hasselbalch equation.