When equal volumes of HCI and NaOH solutions are mixed , the volume becomes double and the corresponding normality (or molarity is reduced to half.
Normality of HCI solution on mixing `=((0.2N) xx(50 mL))/((100 mL)) =0.1N`
`[H^(+)]` in solution `=0.1 N= 0.1 M`
Normality of NaOH solution on mixing `=((0.1N)xx(50mL))/((100mL)) =0.05 N`
`[OH^(-)]` in solution `=0.05 N= 0.05 M`
`[H^(+)]` in solution after neutralisation `=0.1 -0.05 =0.05 M`
pH of solution `=-log [H^(+)] =- log (0.05) = - log (5xx10^(-2))`
`=- (log 5-2 log 10) = (2-log 5) =( 2-0.6989) = 1.301`
