Autoionization

Definition

Autoionization is the process by which molecules of a pure substance react with each other to form ions. A common example is the autoionization of water, where two water molecules produce hydronium and hydroxide ions.

5 Must Know Facts For Your Next Test

1. Autoionization involves the self-ionization of identical molecules.
2. In water, autoionization produces equal concentrations of $H_3O^+$ and $OH^-$ ions.
3. The equilibrium constant for the autoionization of water is denoted as $K_w$.
4. $K_w$ at 25°C is $1.0 \times 10^{-14}$.
5. Autoionization can affect pH calculations in solutions, particularly in very dilute acid or base solutions.

Related terms

Equilibrium Constant:

A number that expresses the ratio of products to reactants at equilibrium for a reversible reaction.

$pH$: A measure of the hydrogen ion concentration; a measure of the acidity or alkalinity of a solution.

$K_w$: The ion-product constant for water at a given temperature, representing the product of hydronium and hydroxide ion concentrations.