Chemistry- PH scale, oxidation and Reduction

pH scale

A scale from 0 to 14 used to measure the relative acidity or alkalinity of an aqueous solution.

Acid (in aqueous solution)

A substance that dissociates to produce hydrogen ions ($H^+$), resulting in a pH less than 7.

Alkali (in aqueous solution)

A soluble base that dissociates to produce hydroxide ions ($OH^-$), resulting in a pH greater than 7.

Ionic equation for neutralisation

$$H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$$

Strong acid

An acid that completely ionises in aqueous solution, fully releasing its $H^+$ ions.

Weak acid

An acid that only partially ionises in aqueous solution, establishing an equilibrium between molecules and ions.

Effect of decreasing pH by 1 unit

The concentration of hydrogen ions ($H^+$) in the solution increases by a factor of 10.

Oxidation

The chemical process involving the addition of oxygen or the loss of electrons by a substance.

Reduction

The chemical process involving the removal of oxygen or the gain of electrons by a substance.

Redox reaction

A reaction in which reduction and oxidation happen simultaneously.