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. 10
B. 12
C. 8
D. 6

Answer

B

Explanation

Millimoles of HCl `=40 xx 0.1 =4.5`
Millimiloes of NaOH `= 10 xx0.45=4.5`
`:. `Volume of solution `=50 mL`
`:. `Moles of NaOH per litre
`=(0.5xx10^(-3)xx1000)/(50)=1 xx 10^(-2)M`
`:.` pOH solution `=- log (1 xx 10^(-2))=2`
`:. pH =14-2=12`