alkali – substance that has a pH level of above 8

(pronounced al-kuh-lye)

To remember the meaning of alkali, use the following mnemonic:

Note: In order to remember the number 8, we have used a rhyme with eight is gate.

After drinking alcohol, I had to lie (alkali) down because I had tried to jump over the gate (pH over 8) and failed.

An alkali is a type of base (a substance that can neutralise an acid) that is soluble in water and produces hydroxide ions when dissolved. Alkalis are found on the right-hand side of the pH scale with pH values greater than 8, and they turn red litmus paper blue. Common examples of alkalis include: sodium hydroxide, potassium hydroxide, and calcium hydroxide, which are often used in cleaning products and for neutralising acids. 

When an alkali reacts with an acid, it undergoes a neutralisation reaction to produce salt and water. Alkalis feel soapy or slippery to touch and can be corrosive (so they must be handed with care in the laboratory). They are important in many industrial processes and everyday applications, from making soap to treating acidic soils.

For more details see whole section in Mammoth Memory on acids, alkalis, bases, and salts.