Question

A 50 mL sample of 0.200 M sodium hydroxide is titrated with 0.200 M HCl. What is the initial pH?

Answer 1

`pH=13.3`

Explanation:

It is well known that in aqueous solution, that

`pH + pOH=14`

`pH=14-pOH`

`pOH=-log_(10)[HO^-]=-log_10(0.200)` `=` `0.70`

`14-0.70=13.3`

`pH` should reasonably be high inasmuch as we measured it BEFORE the start of the titration. Given this, the information regarding the acid was a distractor. What will the `pH` be when the `50.0*mL` volume of `HCl` is added?