A laboratory technician wants to determine the aspirin content of a headache pill by acid–base titration. Aspirin has a Ka of 3.0 × 10-4. The pill is dissolved in water to give a solution that is about 10-2 M and is then titrated with KOH solution. Find the pH at each of the following points, neglecting dilution effects:

Question

A laboratory technician wants to determine the aspirin content of a headache pill by acid–base titration. Aspirin has a Ka of 3.0 × 10-4. The pill is dissolved in water to give a solution that is about 10-2 M and is then titrated with KOH solution. Find the pH at each of the following points, neglecting dilution effects: 
(a) before titration begins. 
(b) at the stoichiometric point. 
(c)at the midpoint of the titration.

Hi. I attempted this but got it wrong.. idk why. Can you help me

3.0 × 10-4(10^-2)=x^2 
x=3.0E^-5M

x=(10^-2)-3.0E-5M 
= 0.09997M