A 20.0mL 0.3M HCl solution is titrated with 0.4M NaOH. What is the exact pH of the solution before titration? And what is the pH at the equivalence point?(are there any straightforward formulas to use on this kind of problem?)
The formula is pH=pKa+log([A-]/[HA])
A- is the base, HA is the acid. So,
Before titration
HCl+H2O->H3O+ + Cl-
pH=-log[H30+]
pH=-log(.100) b/c HCl is a strong acid, it equals [H30+]
pH=1
At equivalence point, pH=7