Would you want to buy the car below?
Probably not! The car is so old that the metal has started rusting.
Rusting is a chemical change.
When iron is exposed to oxygen it will form Iron Oxide.
Only the metal iron rusts. Iron exposed to oxygen and water will rust. Salt speeds up what is quite a slow process.
Should you buy an old car from someone who lives along the coast?
Rusting is an oxidation reaction. Oxidation is a reaction where there is an addition of oxygen.
Magnesium buring in oxygen to form
magnesium oxide is an oxidation reaction.
It is also combustion.
Burning anything is combustion.
Lighting a piece of paper is a
combustion reaction and an
Driving a car which uses petrol or diesel to move is also a combustion reaction.
Some combustion reactions are more useful than others.......
So... rusting, combustion and oxidation will cause a chemical change
Neutralisation will also cause a chemical change.
Neutralisation is when an acid reacts with another substance which is a base.
e.g. Vinegar + Bicarbonate of Soda Sodium Acetate + Water + Carbon Dioxide
The acid is neutralised by the bicarbonate of soda and a neutral solution is formed. During the reaction there is bubbling which is the carbon dioxide. This reaction causes a chmeical change to the vinegar and bicarbonate of soda. New products are formed including Carbon Dioxide which will escape and make a mess whilst doing so!