Question

What is the concentration of H+ ions at a pH = 2?

mol/L
What is the concentration of OH– ions at a pH = 2?
mol/L
What is the ratio of H+ ions to OH– ions at a pH = 2?
: 1

Answer 1

0.01M = [H⁺]; 1x10⁻¹²M = [OH⁻]; Ratio is: 1x10¹⁰

Step-by-step explanation:

pH is defined as -log [H⁺]

For a pH of 2 we can solve [H⁺] as follows:

pH = -log [H⁺]

2 = -log [H⁺]

10^-2 = [H⁺]

0.01M = [H⁺]

Using Keq of water:

Keq = 1x10⁻¹⁴ = [H⁺] [OH⁻]

1x10⁻¹⁴ / 0.01M = [OH⁻]

1x10⁻¹²M = [OH⁻]

The ratio is:

[H⁺] / [OH⁻] = 0.01 / 1x10⁻¹² =

1x10¹⁰