BASES

Many cleaning products, such as soap and oven cleaner, are bases. Bases neutralize (cancel out) acids. Alkalis are bases that dissolve in water. Strong bases, such bleach, are corrosive and burn skin. Bases contain particles called hydroxide ions. The more hydroxide ions a base contains, the stronger it is.

NEUTRAL WASP STING

People used to think that a wasp sting contained a base. In fact, it contains a complex protein, which is neutral. This means that the sting is neither a base nor an acid. The wasp punctures the skin with its hollow stinger. It then pumps the protein through the stinger and into the wound. The protein contains poisons, which cause pain and swelling.

LIMESTONE

Limestone is an important base that is dug from the earth in quarries. It comes from calcium carbonate, which formed millions of years ago from the compressed remains of sea-shells and other marine life. Once quarried, limestone is crushed and used to make cement, fertilizers, paints, and ceramics.

Copyright © 2007 Dorling Kindersley