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

Give an example of decomposition reaction. Describe an activity to illustrate such a reaction by heating.

Accepted Answer

An example of a decomposition reaction is the decomposition of ferrous sulphate crystals. The reaction is as follows:

${FeSO}_{4} . 7 H_{2} O (s) \overset{Heat}{\to} {FeSO}_{4} (s) + 7 H_{2} O (l) 2 {FeSO}_{4} (s) \overset{Heat}{\to} {Fe}_{2} O_{3} (s) + {SO}_{2} (g) + {SO}_{3} (g)$

An activity to illustrate a displacement reaction by heating can be given as follows:

Experiment: Take about $2 g$ of ferrous sulphate crystals in a dry boiling tube. Note the colour of the ferrous sulphate crystals. Heat the boiling tube over the flame of a burner or spirit lamp.

Observation: It is observed that the green colour of ferrous sulphate crystals changes to reddish brown and smell of burning sulphur is observed.

This is a decomposition reaction because a single reactant breaks down to give simple products. Ferrous sulphate crystals have the formula ${FeSO}_{4} . 7 H_{2} O$ . On heating, these lose water molecules and the colour of the crystals changes. It then decomposes to ferric oxide, sulphur dioxide and sulphur trioxide. Ferric oxide is a reddish brown solid while others are gases.

Give an example of decomposition reaction. Describe an activity to illustrate such a reaction by heating.

Important Questions on Chemical Reactions and Equations

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