Classwork Exercise and Series (Chemistry-SS2): Types of Chemical Reactions

Chemistry, SS 2 Week: 4

Topic: Types of Chemical Reactions

Chemical reactions are changes in which some new chemical substances are formed. The substances which undergo the chemical change are known as reactants while the new substances formed are called products. Here’s a list of the different types of reactions, with examples of each type included.

Synthesis reaction or combination reaction: This is a reaction in which two or more elements or compounds combine to form a single product. This type of reaction follows the general equation

Where A and B may be either elements or compounds.

Here are some examples:

Sodium    ChlorineSodium Chloride

S_(s)      +   O_2(g) ———>  SO_2(g)
sulphur    oxygen    sulphur dioxide

2 S_(s)   +    3 O_2(g) ———>  2 SO_3(g)
sulphur   oxygen sulphur trioxide

 2 Fe(s)   +   O_2(g)  ———>  2 FeO_(s)
iron   oxygen      iron (II)  oxide

Decomposition reaction: In this type of reaction, a single reactant, a compound, breaks into two or more parts. Often these are the most difficult to predict. Here is the general equation:

Where A and B may be either elements or compounds.

Here are some examples of decomposition reactions:

Single replacement or displacement reaction: In this type of reaction, a more active element replaces a less active element in a compound. Among the halogens, F₂ is the most active halogen and the activity of the halogens decreases as you go down the group. General equation:

Where A is a metal.

Here is an example of a displacement reaction in which a metal is involved:

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