Name: Preparation of Insoluble Salts
Uploaded: 2019-07-19
Duration: 2 min 50 s
Description: A precipitation reaction is an example of a "Double Displacement Reaction" and is one of the ways to produce insoluble salts. Let us learn about it.

Question

What are decomposition reactions? Give one experiment to demonstrate a decomposition reaction. How do they differ from combination reactions.

Accepted Answer

The reactions in which a compound breaks up into two or more simpler substances are known as decomposition reactions. These reactions generally take place when energy is supplied in the form of heat, light, electricity or catalysts.

An experiment to demonstrate a decomposition reaction can be shown by using lead nitrate power. That is,

Experiment: Take about 2g of lead nitrate powder in a dry boiling tube. Hold the boiling tube with a pair of tongs and heat it over the flame as shown in the figure. Observe.

Observation: It is observed that the pungent-smelling brown fumes come out of the test tube. This indicates the following decomposition reaction. The brown vapour is due to the formation of ${NO}_{2}$ .

$2 Pb ({NO}_{3})_{2} (s) \to 2 PbO (s) + 4 {NO}_{2} (g) + O_{2} (g)$

Conclusion: This is a decomposition reaction because a single reactant breaks down to give different products.

The decomposition reactions are reverse of combination reactions as combination reaction is a chemical reaction in which two or more substances combine to form a single product.

What are decomposition reactions? Give one experiment to demonstrate a decomposition reaction. How do they differ from combination reactions.

Important Questions on Chemical Reactions and Equations

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