Copyright © 2007 Dorling Kindersley
The sour taste of food such as lemons is due to acids. Acids in food are weak, but they can sting if they touch a cut on your skin. Strong acids, such as sulphuric acid in car batteries, are much more dangerous as they can burn through materials. Acid compounds all contain hydrogen. They dissolve in water to produce particles called hydrogen ions. The more hydrogen ions an acid contains, the stronger an acid it is.