What will be the `pH` of a solution formed by mixing `40 ml` of `0.10 M HCl` with `10 ml` of `0.45 M NaOH`?

Options

A. `12`
B. `10`
C. `8`
D. `6`

Answer

A

Explanation

`M.eq.` of `0.10 M HCl =(0.10)/(1000)xx40=0.004 M`
`M.eq.` of `0.45 M NaOH=(0.45xx10)/(1000)=0.0045 M`
Now left `[OH^(-)]=0.0045-0.004=5xx10^(-4)M`
Total volume `= 50 ml`
`[OH^(-)]=(5xx10^(-4))/(50)xx1000` , `[OH^(-)]=1xx10^(-2)`
`pOH=2`, `pH=14-pOH=12`