Chemicals are all around us – everything is made of ‘chemicals’! We also use many simple chemical reactions in our everyday lives.
The foods we eat contain natural chemicals we need to live (like carbohydrates, fats and sugars); we burn carbon containing substances like wood, coal, gas and petrol in order to stay warm, generate electricity and transport ourselves around; the clothes we wear are made from natural substances like cotton, or artificial textiles like polyester; the drugs we take when we have a headache or an injury are all specially developed chemicals.
One of the most important new uses of chemicals has been the invention of plastics. These are made originally from crude oil buried deep underground (this oil also provides us with jet fuel, diesel and petrol, tar which we make roads with and motor oils and greases). Plastics have replaced all sorts of other substances like wood, metal and natural cloths.
Two simple kinds of chemicals are acids and bases. Acids are what make oranges and lemons taste sharp and tangy, are present in vinegar and fizzy drinks, and are used to digest food in your stomach which is why it tastes so horrible when you vomit. Alkaline substances in the home include baking soda, soap, milk of magnesia and ashes. When acids and alkalis are mixed the counteract each other and become useful. Since bee stings are acidic, some people recommend putting baking soda on a bee sting. Wasp stings are alkaline so putting acidic substances on the sting is supposed to make it hurt less!
Another reaction we see everyday is between hydrophobic (water-hating) and hydrophilic (water-loving) molecules. Fats are hydrophobic and so don’t mix well with water – that’s why you get little blobs of fat floating on the surface. This is a problem when we’re trying to clean our dishes, which is why we use soaps and washing up liquids! Soaps have a special structure that forms little balls to trap the fatty dirt in. The inside of the ball is hydrophobic, just like fats, while the outside is hydrophilic and so can be washed away by the water. Shower gels and shampoos work in the same way!