Find the `pH` of solution prepared by mixing `25 ml` of a `0.5 M` solution of `HCl, 10 ml` of a `0.5 M` solution of `NaOH` and `15 ml` of water

Options

A. 0.8239
B. 1.0029
C. 1.0239
D. 1.8239

Answer

A

Explanation

We know that for HCl and NaOH, m.e=m.e
m.e of HCl `=0.5 xx 25=12.5`
m.e of NaOH `=0.5 xx 10=5.0`
m.e. of HCl in the resultant mixture =12.5-5.0=7.5
total volume =(25+10+15)ml=50ml
Normality of HCl `=(m.e.)/("Vol(ml)")=(7.50)/(50)`
Molarity `=(7.50)/(50)`
`[H^(+)]=[HCl]=(7.50)/(50)`
`pH=-log"" (7.50)/(50)=0.8239`