Question

What would you observe when crystals of copper $(II)$ sulphate and iron $(II)$ sulphate are separately heated in two test tubes?

Answer 1

Hint: The crystals of copper $(II)$ sulphate have molecular formula of $CuS{O_4}.5{H_2}O$.The molecular formula of iron $(II)$ sulphate is $FeS{O_4}.7{H_2}O$. The heating of these compounds is known as thermal decomposition of the compounds. This is a very important concept of inorganic chemistry.

Complete step by step answer:
So as we know that the crystals of copper $(II)$ sulphate have a molecular formula of $CuS{O_4}.5{H_2}O$. So when $CuS{O_4}.5{H_2}O$ is heated in a test tube, it undergoes a decomposition reaction. During the reaction we can observe some liquid droplets on the upper side of the test tube, it is due to the water molecules of the hydrated crystals of copper $(II)$ sulphate. Before heating the colour of the crystals of copper $(II)$ sulphate was blue, but after undergoing decomposition reaction it turns white. The reaction can be written as:
$CuS{O_4}\xrightarrow{\Delta }CuO(s) + {O_2}(g) + S{O_2}(g)$
Similarly when we heat iron $(II)$ sulphate in a test tube, it undergoes decomposition reaction. On heating it loses water molecules and turns light green . On further heating it undergoes the following reaction:
$FeS{O_4}\xrightarrow{\Delta }F{e_2}{O_3}(s) + S{O_2}(g) + S{O_3}(g)$

Additional information:
Copper sulphate is a very important compound. It is used as fungicide, algaecide, root killer, and herbicide in both agriculture and non-agricultural sectors. Iron $(II)$ sulphate is also a very important compound. It is used to cure anaemia in human beings which occurs due to the deficiency of red blood cells caused by having too little iron in the body.

Note:
Always remember that both crystals of copper $(II)$ sulphate and iron $(II)$ sulphate contain molecules of water in it. So whenever we heat the crystals , it will lose the water molecules first and after that the compound will undergo decomposition reaction. The molecular formula of copper $(II)$ sulphate is $CuS{O_4}.5{H_2}O$ and the molecular formula of iron $(II)$ sulphate is $FeS{O_4}.7{H_2}O$