Question

If enough H+ ions are added to pure water to raise the concentration of the solution to ten times higher than the original concentration, what is the resulting OH⁻ concentration of the solution?

1) 10⁻⁵ M
2) 10⁻⁶ M
3) 10⁻⁷ M
4) 10⁻⁸ M

Answer 1

When the concentration of H+ ions in pure water is increased tenfold, the OH- concentration can be found by using the ion product of water, resulting in a new OH- concentration of 1.0 × 10^-8 M, which is option 4.

Step-by-step explanation:

If the concentration of H+ ions is increased to ten times the original concentration in pure water, the new concentration of H+ would become 1.0 × 10-6 M. Since the product of concentrations of H+ and OH- ions must always equal 1.0 × 10-14 at 25 °C, we can determine the new OH- concentration.

[H+] × [OH-] = 1.0 × 10-14
1.0 × 10-6 M × [OH-] = 1.0 × 10-14
[OH-] = ç(1.0 × 10-14 / 1.0 × 10-6) = 1.0 × 10-8 M

Therefore, the resulting OH- concentration of the solution is 1.0 × 10-8 M, which corresponds to option 4 in the given choices.