Question

What is the pH of the resulting solution when equal volumes of $0.1\, M \,NaOH$ and $0.01\, M$ $HCl$ are mixed ?

• A. 7
• B. 1.04
• C. 12.65
• D. 2

Answer 1

Answer: (C)

12.65

Answer 2

${N_1V_1 - N_2V_2 = N.V.}$
${0.1 \times 1 - 0.01 \times 1 = N \times 2 }$
${[OH^{-}] = N_R = \frac{0.09}{2} = 0.045 \; N }$
pOH = - log (0.045) = 1.35
$\therefore$ pH = 14 - pOH = 14 - 1.35 = 12.65