Acids, Bases and Alkalis

Bases are substances that can react with acids and neutralise them.

Alkalis are bases that are soluble in water. The pH scale measures how acidic or alkaline a substance is. Substances with a pH lower than 7 are acidic, those with a pH of 7 are neutral and those with a pH greater than 7 are alkaline.

The pH scale
The chemical properties of many solutions enable them to be divided into three categories - acids, alkalis and neutral solutions. The strength of the acidity or alkalinity is expressed by the pH scale.
solutions with a pH less than 7 are acidic
solutions with a pH of 7 are neutral
solutions with a pH greater than 7 are alkaline.

If universal indicator is added to a solution it changes to a colour that shows the pH of the solution.
 
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