A 0.0500 L solution of a 0.1000 M solution of a weak acid, HY. Ka = 1.80 x 10^-8. The solution is titrated with 0.1000 M NaOH. The pH at the equivalence point is approximately 10.20

Question

A. Find the net ionic equation
B. Determine the pH of the original weak acid solution. (before the titration took place = initial pH)

Answer 1

A. You want the net ionic equation FOR WHAT? THE TITRATION? THE IONIZATION OF HY? THE HYDROLYSIS OF HY?

B. ............HY + H2O ==> H3O^+ + Y^
I................0.1......................0.............0
C................-x........................x..............x
E.............0.1- x.....................x...............x
Ka = (H^+)(Y^-)/(HY)
1.8E-8 = (x)(x)/(0.1-x)
Solve for x = (H3O^+) and convert to pH.

Answer 2

Thank you for your help on B !
The net ionic equation is for the titration

Answer 3

The molecular equation for the titration is as follows:
HY(aq) + NaOH(aq) ==> NaY(aq) + H2O(l)
Net ionic equation is as follows:
HY(aq) + OH^-(aq) --> Y^-(aq) + H2O(l)