Question

Which of the following solution will have a pH exactly equal to 8 ?

• A. 10–8 M HCl solution at 25⁰C
• B. 10–8 M H+ solution at 25⁰C
• C. 2 × 10–6 M Ba(OH)2 solution at 25⁰C
• D. 10–5 M NaOH solution at 25⁰C

Answer 1

Answer: (B)

10–8 M H+ solution at 25⁰C

Answer 2

(1) At 25⁰C, [H+] in a solution of 10–8 M HCl > 10–7 M.

(2) [H+] = 10–8 M.

(3) [OH–] = 4 × 10–6 M

$\Rightarrow$[H+] = 2.5 × 10–9 M.

(4) [H+] = 10–9 M.