Why does the color of copper sulphate change when an iron nail is kept in it? Justify your answer.

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The color of copper sulphate changes to pale green from blue in the iron and copper reaction as iron replaces copper and forms ferrous sulfate and because of this displacement, the color change happens. The reaction of copper sulfate and iron nail:

  • Iron is positioned above Copper in the reactivity series, indicating that iron has higher reactivity than copper.
  • Therefore, when iron and copper sulphate reacts, iron displaces copper from it to generate ferrous sulphate, which changes the solution’s color from blue to pale green.

CuSO4(s) + Fe(s) → FeSO4(aq) + Cu(s)

Copper sulphate + Iron → Ferrous sulphate + Copper

Uses of Copper Sulphate

  • This compound’s pentahydrate, CuSO4.5H2O, is utilised as a fungicide because it may kill a variety of fungi.
  • Benedict’s solution and Fehling’s solution, which are used to test for reducing sugars, both include copper sulphate.
  • Blood samples are also examined for conditions like anaemia using this method.
  • CuSO4 and KMnO4 (potassium permanganate) are combined to create an oxidant that can be used to convert 1o
  • Additionally, it serves as a fixative for the dye when using vegetable dyes.
  • Liquid resistors with resistive elements can be made by dissolving copper sulphate in water.
  • Since it may also lend colour to cement, ceramics, and other metals, it can also be utilised as a decorative element.
  • In order to shield the printed paper from bugs, bookbinding glues also contain copper sulphate.


Why does the color of copper sulphate change when an iron nail is kept in it? Justify your answer.

In the iron and copper reaction, copper is replaced by iron, which results in the formation of ferrous sulphate. As a result of this displacement, the colour of copper sulphate changes from blue to pale green.

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