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Chemistry > Types of Reaction


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There are many types of chemical reaction that can take place in school chemistry. The main reactions are listed here with a short description for each.

Endothermic

These are reactions that take heat from their surroundings as the substances react. Mixing sodium carbonate with ethanoic acid in a test tube creates an endothermic reaction where the test tube becomes noticeable older to the touch. Thermal decomposition reactions that need a constant supply of heat are also a type of endothermic reaction. Electrolysis what requires a constant electrical supply is also classed as an endothermic reaction.

Exothermic

Reactions that give out heat are known as exothermic reactions. Combustion reactions where wood or fuel burns is an exothermic reaction as are reactions which warm a test tube such as the reaction between sodium hydroxide and water.

Electrolysis

Passing electricity through some compounds makes them split into simpler ones. If you use electrolysis to separate copper chloride, you end up with copper and chlorine.

Thermal Decomposition

Thermal decomposition uses heat to break down compounds into other substances. An example is cracking where long chain molecules in thick oils are broken down into more useful substances. Breaking down the calcium carbonate in limestone into carbon dioxide and calcium oxide within a blast furnace is another example.

Neutralisation

When an acid reacts with a base to produce a neutral solution or a salt, neutralisation has occurred. An example would be hydrochloric acid reacting with sodium hydroxide to form a neutral solution of sodium chloride.

Reduction

An example is when iron is produced form iron oxide. It occurs when substances lose oxygen.

Oxidisation

The opposite of reduction, oxidation occurs when substances gain oxygen. Rusting of metals is an example of oxidation

Displacement

These reaction occur when a more reactive element replaces a less reactive one in a compound. When zinc and copper oxide are reacted, you end up with zinc oxide and copper.