The concentrations of hydrogen ions (H+) and hydroxide ions (OH-) in an aqueous solution are inversely proportional to each other. This means that as the concentration of one increases, the concentration of the other decreases. This relationship is defined by the ionic product of water (Kw):

Kw = [H+][OH-] = 1.0 x 10^-14 at 25°C

Here's what this means:

* Neutral Solution: In a neutral solution, the concentrations of H+ and OH- are equal. This occurs when both are 1.0 x 10^-7 M.

* Acidic Solution: In an acidic solution, the concentration of H+ is greater than the concentration of OH-. This means the [H+] > 1.0 x 10^-7 M and the [OH-] < 1.0 x 10^-7 M.

* Basic Solution: In a basic solution, the concentration of OH- is greater than the concentration of H+. This means the [OH-] > 1.0 x 10^-7 M and the [H+] < 1.0 x 10^-7 M.

Key Points:

* The product of [H+] and [OH-] always equals Kw, even if the solution is acidic or basic.

* The pH scale, which measures acidity/basicity, is related to the concentration of H+:

* pH = -log[H+]

* Lower pH values indicate higher acidity (more H+).

* Higher pH values indicate higher basicity (more OH-).

Example:

If the concentration of H+ in a solution is 1.0 x 10^-5 M, then the concentration of OH- can be calculated using Kw:

[OH-] = Kw / [H+] = (1.0 x 10^-14) / (1.0 x 10^-5) = 1.0 x 10^-9 M