Formation of salts
In addition to water, a new compound is formed from the rest of the acid and alkali molecule. This is known as a salt.
In chemistry, a salt is a compound formed by an acid and an alkali. In everyday English though, the word refers to only one particular type of salt: Sodium chloride or table salt.
Sodium chloride (NaCl) is formed when hydrochloric acid is neutralised by sodium hydroxide.
If the water is evaporated away then only the salt remains.
As mentioned earlier, heartburn arises when tissue (protein) lining the oesophagus is denatured by a reflux of stomach acid.
Remedies for heartburn are called antacids and they work by neutralising the stomach acid and so soothing the oesophagus.
A common ingredient in antacids is the alkali magnesium hydroxide, MgOH2.