Question

The crystals of ferrous sulphate on heating gives:
a.) $FeO+S{{O}_{2}}+{{H}_{2}}O$
b.) $F{{e}_{2}}{{O}_{3}}+{{H}_{2}}S{{O}_{2}}+{{H}_{2}}O$
c.) $F{{e}_{2}}{{O}_{3}}+S{{O}_{2}}+S{{O}_{3}}$
d.) $FeO+S{{O}_{3}}+{{H}_{2}}S{{O}_{2}}+{{H}_{2}}O$

Answer 1

Hint: The formula of ferrous sulphate is $FeS{{O}_{4}}.7{{H}_{2}}O$. When we heat ferrous sulphate it loses its water molecules and forms a molecule of anhydrous ferrous sulphate and also the color of the ferrous sulphate molecule changes from green to white.

Complete step by step answer:
 Decomposition reaction is reaction in which a chemical compound break down into two or more substances. The general equation for decomposition reaction is:
\[AB\to A+B\]
Double decomposition reaction is the reaction in which reactants interchange their ions (positive or negative) and this leads to the formation of new compounds. The general equation for double decomposition reaction is:
$AB+CD\to AD+CB$
Decomposition reaction is of three types thermal, electrolytic and pyrolytic decomposition reaction.
On heating, ferrous sulphate losses it water molecules and form molecule of anhydrous ferrous sulphate which leads to the change in color of the crystal from light green to white and on further heating of ferrous sulphate it breaks down into ferric oxide, sulphur trioxide and sulphur dioxide.

The reactions involved are mentioned below:
\[2FeS{{O}_{4}}\xrightarrow{heat}F{{e}_{2}}{{O}_{3}}+S{{O}_{2}}+S{{O}_{3}}\]
This is a decomposition reaction because in this reaction ferrous sulphate decomposes into more than one product.
Hence the correct answer is option (C) i.e. $F{{e}_{2}}{{O}_{3}}+S{{O}_{2}}+S{{O}_{3}}$ ferrous sulphate breaks down into ferric oxide, sulphur trioxide and sulphur dioxide.
So, the correct answer is “Option C”.

Note: The process of decomposition of ferrous sulphate is thermal decomposition reaction. In this type of decomposition reaction the reaction is activated by the thermal energy. Another example of thermal decomposition reaction is the decomposition of calcium carbonate to calcium oxide and carbon dioxide.