Question

The white anhydrous copper sulphate is heated to high temperature, it gives:
A. \[CuS{O_4}.5{H_2}O\]
B. \[CuS{O_4}.{H_2}O\]
C. \[CuS{O_4} + S{O_2}\]
D. \[CuO\]

Answer 1

Hint: Anhydrous Copper sulphate when strongly heated further it gets converted into an oxide of Cu. So students try to recollect the chemical reaction when copper sulphate is heated to a high temperature. The crystals of hydrated copper sulphate salt are blue in colour. When heated, the salt loses its water of crystallization and turns white.

Complete step by step answer:
Copper sulphate \[\left( {CuS{O_4}.5{H_2}O} \right)\] when heated loses its water of crystallization to form anhydrous copper sulphate and when heated further it gets converted in to an oxide of. The chemical reaction of the effect of heating on anhydrous Copper sulphate is as follows :
$2CuS{O_4}\xrightarrow{{{{750}^o}C}}2CuO + 2S{O_2} + {O_2}$

Hence the correct answer is D.

Additional information:
Anhydrous copper sulphate-It is also known as blue vitriol. It is prepared by dissolving cupric oxide or hydroxide or carbonate in dilute \[{H_2}S{O_4}\].It is blue crystalline solid, soluble in \[{H_2}O\]. It is used in electroplating, Electrotyping and dyeing. It is also used as Fungicide or Germicide in agriculture. Hydrated copper sulphate \[\left( {CuS{O_4}.5{H_2}O} \right)\] is blue which on heating loses its water of crystallization to form anhydrous\[CuS{O_4}\]a white compound.
Cupric oxide - \[CuO\] is insoluble in water. It readily dissolves in dilute acids. \[CuO\] is reduced to \[Cu\] by\[{H_2}\] or \[C\] under hot conditions. It is known as black oxide of copper and it is present as tenorite in nature. It is black powder which is insoluble in water but dissolves in acids. It gives greenish blue color to glass etc. To remove sulphur from petroleum. In the estimation and detection of carbon.

Note: When we heat blue colored Copper sulfate \[\left( {CuS{O_4}.5{H_2}O} \right)\], it is converted into white coloured anhydrous copper sulphate (\[CuS{O_4}\]). After that when we add water into it again, the colour of copper sulphate is changed to blue. Always remember that this type of changes are known as reversible chemical change.