Chemicals in the lab and home
Household substances are all chemicals, including food. You may find some of these chemicals in the laboratory as well. Many are obtained from natural sources and others are made artificially, using chemical reactions.
Some household substances, such as cleaning products, are made of quite harmful chemicals - hazard labels are useful in warning of danger at home as well as in the laboratory.
Carbonates and hydrogen carbonates break down when heated in the lab, forming carbon dioxide. Similarly, cooking involves chemical reactions in which new substances are formed.
Natural substances are made in living organisms or come from the Earth. For example, they may be found in the Earth's crust, atmosphere or oceans. Artificial substances are made by chemists using chemical reactions in the laboratory or chemical factory. You need to be able to discuss any differences between natural and artificial substances.
Table salt is sodium chloride. Natural table salt is extracted from salt in salt mines or by evaporating the water from sea water. However, sodium chloride can also be made using chemical reactions. For example:
sodium + chlorine → sodium chloride
sodium hydroxide + hydrochloric acid → sodium chloride + water
The sodium chloride formed in a laboratory is chemically identical to sodium chloride found in nature (assuming other substances have been removed to make it pure). However, people often prefer natural chemicals, especially in food, clothing and cosmetics.
Food tastes and smells nice because of the chemicals it contains. Some flavours are due to simple substances, such as sodium chloride, and you cannot tell the difference between natural and artificial sources. Other flavours are due to more complex substances, such as vanilla flavouring.
Ice cream contains vanilla flavouring. Artificial vanilla is usually a substance called ethyl vanillin. This has a much stronger taste and smell than natural vanilla. It is also cheaper to make than natural vanilla, which has to be extracted from vanilla beans. People with a good sense of taste can tell the difference between the two types of vanilla, because the natural vanilla is a mixture of substances.