Question

that will be the resultant pH when 200 ml of an aqueous solution of HCl (pH = 2.0) is
ixed with 300 ml of an aqueous solution of NaOH (pH = 12.0)?
1) 27
(B) 11.3
(93
(D) 10.3
A
C.​

Answer 1

pH 2.0 of HCl corresponds to the hydrogen ion concentration of 0.01 M.

The number of moles of hydrogen ions present are 0.01×0.2=0.0020

pH 12.0 of NaOH corresponds to hydroxide ion concentration of 0.01 M.

The number of moles of hydroxide ions present are 0.01×0.3=0.0030

Out of 0.0030 moles of hydroxide ions, 0.0020 moles will be neutralized with 0.0020 moles of hydrogen ions.

Hence, the hydroxide ion concentration remaining is

0.5

0.0010

=0.0020M

Hence, the pOH of the solution is pOH=−log[OH

−

]=−log0.0020=2.699

The pH of the solution is pH=14−pOH=14−2.699=11.301≈11.