To study decomposition reactions.
Decomposition is a type of chemical reaction. It is defined as the reaction in which a single compound splits into two or more simple substances under suitable conditions. It is just the opposite of the combination reaction.
In a combination reaction, a substance is formed as a result of chemical combination, while in a decomposition reaction, the substance breaks into new substances.
For example: The digestion of food in our body is accompanied by a number of decomposition reactions. The major constituents of our food such as carbohydrates, fats, proteins, etc.,decompose to form a number of simpler substances. These substances further react, releasing large amounts of energy, which keeps our body working.
The general equation that describes a decomposition reaction is:
Decomposition reactions can be classified into three types:
Thermal decomposition is a chemical reaction where a single substance breaks into two or more simple substances when heated. The reaction is usually endothermic because heat is required to break the bonds present in the substance.
Photo decomposition is a chemical reaction in which a substance is broken down into simple substances by exposure to light (photons).
If the decomposition is carried out in the presence of manganese dioxide (MnO2), it takes place at a lower temperature. In this case, MnO2 is used as a catalyst.
Hydrated oxalic acid (H2C2O4.2H2O) decomposes into oxalic acid and water when heated.
Electrolytic decomposition may result when electric current is passed through an aqueous solution of a compound. A good example is the electrolysis of water.
Silver bromide also decomposes in the same way.
Most decomposition reactions require energy either in the form of heat, light or electricity. Absorption of energy causes the breaking of the bonds present in the reacting substance which decomposes to give the product.
Let’s discuss the decomposition reaction of ferrous sulphate crystals by the action of heat.