Question

Which equation correctly shows how you could calculate [OH-] from [H+]

Answer 1

`Kw = [H+][OH-]`

Step-by-step explanation:

For a given solution H+ refers to the hydrogen ion concentration and is indicative of the acidity of the solution. The more the [H+] concentration, higher is the acidity. Similarly, OH- refers to the hydroxide ion concentration and reflects the basicity of the solution. A solution with a higher OH- concentration is said to be basic.

The two are related by considering the dissociation of water:

`H2O(l)\rightleftharpoons H+(aq)+ OH-(aq)`

The dissociation constant for water, Kw is:

`Kw = [H+][OH-]\\\\where\ Kw = 10^(-14) \\\\10^(-14) = [H+][OH-]\\`

`[H+] = (10^(-14))/([OH-])`

Answer 2

[OH⁻] = 10⁻¹⁴/[H⁺].

Step-by-step explanation:

∵ [H⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H⁺].