What an acid is
Acids, bases and salts are used for many jobs in everyday life. Start by sorting some familiar things.
Assignment 7.1
Sort these everyday things into acids, bases and salts: lime juice, oral rehydration salts, antacid tablets, milk of magnesia, toothpaste, vinegar, table salt, slaked lime, soap, vitamin C tablets, saline.
The acids in the list
Lime juice, vinegar and vitamin C are acids. In the laboratory you have also used hydrochloric acid (HCl), sulphuric acid (H2SO4) and nitric acid (HNO3).
Figure to be added
Look at their formulae: every one contains hydrogen (H).
Acid
An acid is a chemical compound that releases hydrogen ions (H+) in aqueous solution.
Hydrochloric acid ionises in water like this:
HCl (aq) → H+ (aq) + Cl- (aq)