What is the resulting pH????? CAN ANYONE HELP ME WITH THIS PROBLEM!!!?

Question

Consider an acid, HA, with pKa = 4.282. 0.095 moles of hydroxide ion are added to 20.3mL of a 0.896M solution of the acid. What is the resulting pH?

Can Anyone help me with this problem!?!?

Answer 1

Use the Henderson Hasselbaugh equation:

pH = pKa + log(base/acid)

Now, the base and acid can either be expressed as concentrations (molarity) or number of moles.

Let's see how many moles of acid we have.

M = mol/L

0.896 = mol/.0203

moles = 0.018

Now, use the H-H equation.

pH = pKa + log(base/acid)

pH = 4.282 + log(.095/.018)

pH = 5.004

Hope I helped :)