Which of the following forms a solution with a pH of 13.7?

Question

Answer choices

0.02M solution of NaOH

None of the above

0.5M solution of NaOH

0.04M solution of Mg(OH)2

0.5M solution of HClO4

Answer 1

0.02 M NaOH => 0.02 M OH-

pOH = -log 0.02 = 1.70

pH = 14 - 1.70 = 12.30

0.5 M NaOH => 0.5 M OH-

pOH = -log 0.5 = 0.30

pH = 14 - 0.30 = 13.7

0.04 M Mg(OH)2 => 2x0.04 M OH- = 0.08 M OH-

pOH = -log 0.08 = 1.10

pH = 14 - 1.1 = 12.9

0.5 M HClO4

This is a strong acid and produce a pH significantly less than 7, so rule this out.

0.5 M NaOH WILL PRODUCE A SOLUTION WITH A pH OF 13.7