Answer is: Concentration of OH⁻ is 100 times greater than what it was at pH 5.
When pH is below 7, solution is acidic, pH greater that 7 solution is basic and pH equals to 7, solution is neutral.
pH + pOH = 14.
pOH₁ = 14 - 5 = 9; first solution.
pOH₂ = 14 - 7 = 7; second solution.
pOH = -log[OH⁻].
[OH⁻]₁ = 10⁻⁹ M, measure of hydroxide ion (OH⁻) concentration of first solution.
[OH⁻]₂ = 10⁻⁷ M, measure of hydroxide ion (OH⁻) concentration of second solution.
[OH⁻]₂ / [OH⁻]₁ = 10⁻⁷ M / 10⁻⁹ M.
[OH⁻]₂ / [OH⁻]₁ = 100.
