Neutralisation and the pH Scale

Vocabulary flashcards based on section C5.7 covering neutralisation, acids, alkalis, indicators, and the pH scale.

Acid

A substance that produces hydrogen ions ($H^+(aq)$) when dissolved in water.

Alkali

A substance that produces hydroxide ions ($OH^-(aq)$) when dissolved in water.

Neutralisation reaction

A reaction between an acid and an alkali where hydrogen ions ($H^+(aq)$) react with hydroxide ions ($OH^-(aq)$) to form water.

Ionic equation for neutralisation

The reaction equation between hydrogen ions and hydroxide ions: $H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$.

Indicator

A substance that changes colour when added to an acidic or alkaline solution.

Universal indicator

A chemical indicator made from a mixture of dyes that shows colour changes to tell how acidic or alkaline a solution is.

pH scale

A numerical scale used to measure acidity or alkalinity, where a value of $7$ is neutral, less than $7$ is acidic, and greater than $7$ is alkaline.

pH sensor

A device with a glass probe attached to a data logger that measures and records pH changes over time.