basic, ionic salt of an alkali metal or alkaline earth metal chemical element

In chemistry, an alkali is an aqueous (from water) solution with a pH value of more than 7. The word 'Alkali' comes from the Arabic 'qali' meaning 'from the ashes' since ashes mixed with water used as cleaning products (such as soaps) are made of alkali materials.

An alkali is where a base is dissolved in water. Often it is the salt of an Alkali metal
An alkali is the opposite to an acid and can be neutralised (brought down to pH 7) by adding acid.


  • It feels soapy
  • It is corrosive (it can burn your skin away)
  • The higher the number is over 7 on the pH scale the stronger the alkali is.
  • Highly soluble (can be dissolved) in water
  • They have a bitter taste
  • Turns red litmus paper blue
  • Can conduct electricity due to the presence of mobile ions
  • Is blue or purple on universal indicator



Like acids, alkalis can be weak or strong, depending on the nature and the concentration of the ionic salt composing it. The strength of an alkali can be found using universal indicator. Also like acids, the strength of an alkali is rated using the pH scale.

For example, soap and toothpaste contain weak alkalis, while cleaning products often contain strong ones.

Sodium Hydroxide

Examples of common Alkalis


Uses of common Alkalis


Oxides and Hydroxides


Metal oxides and metal hydroxides are two types of base. When neutralised (an acid is added) they produce a salt and water. The type of salt produced depends on the acid and base.


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