Question

Write the formula of blue vitriol.

Answer 1

Hint: Blue vitriol is an inorganic compound also known as copper sulphate. The compound is blue in colour.

Complete step by step solution:
- Copper(II) Sulphate also known as copper sulphate is an inorganic compound with a formula \[CuS{{O}_{4}}{{({{H}_{2}}O)}_{x}}\], here x ranges from 0 to 5. Usually it exists as pentahydrate form. Its old names are blue vitriol. Other names of copper sulphate are vitriol of copper and roman vitriol.
-Pentahydrate \[CuS{{O}_{4}}5{{H}_{2}}O\] is a common salt which has a bright blue colour. It dissolves in water by releasing heat and gives an aqua complex\[{{[CuS{{O}_{4}}{{({{H}_{2}}O)}_{6}}]}^{2+}}\], and has an octahedral geometry.
-Anhydrous copper sulphate is a grey powder.
-It is produced industrially by treating copper metal with hot concentrated sulphuric acid. It can be also produced by slowly leaching copper ore in air.
-\[CuS{{O}_{4}}.5{{H}_{2}}O\] decomposes before melting. On heating at \[{{63}^{o}}C\] it loses two water molecules. A two more is lost when temperature increases to \[{{109}^{o}}C\] and the final water molecule is released at \[{{200}^{o}}C\]. Dehydration proceeds by decomposition of tetraaquacopper moiety, two opposing aqua groups are lost and it gives diaqua copper moiety. In the second dehydration step the next two aqua groups are lost. When the last aqua group also leaves complete dehydration of copper sulphate occurs at \[\,{{650}^{o}}C\]. It decomposes to Copper(II) oxide and sulphur trioxide.
-Pentahydrate of copper sulphate is used as a fungicide. The fungus on grapes, melons and other berries can be controlled by Bordeaux mixture. It is a mixture consisting of copper sulphate and calcium hydroxide. Copper sulphate has its application in horticulture also.

Note: Blue vitriol is often mixed up with green vitriol. Green vitriol is crystalline ferrous sulphate.