Open letter to South Africa’s students‚ universities and government‚ represented by Minister in the .
FEW substances are made of only one chemical, such as pure water or pure salt.
Most things are combinations of several chemicals. Compounds are formed when two or more substances are mixed together and the chemical bonds that hold them together break apart and recombine in a new substance.
A mixture is formed when substances are mixed together but do not react, so can be easily separated again because they have not changed. - The New Children's Encyclopedia, Dorling Kindersley