When iron nails are dipped in copper sulphate solution, a chemical reaction occurs where the iron displaces the copper, resulting in a coating on the nail and a colour change in the solution.
The Chemical Transformation
Based on the provided reference, dipping an iron nail into a copper sulphate (CuSO₄) solution initiates a displacement reaction. Iron is more reactive than copper, allowing it to push copper out of the copper sulphate compound.
The specific changes observed are:
- Change to the Iron Nail: The iron nail undergoes a transformation as copper from the solution is deposited onto its surface.
- Change to the Solution: The colour of the copper sulphate solution changes due to the formation of a new substance.
Let's break down the observable changes as described in the reference:
Observable Changes
The reference explicitly states the key outcomes of this reaction:
| Item | Initial State | Final State |
|---|---|---|
| Iron Nail | Typical metallic iron colour | Coated with a brown layer of copper |
| Solution | Blue (due to copper sulphate) | Changes colour to pale green (due to iron sulphate formation) |
- Reference Extract: "When an iron nail is dipped in CuSO4 solution iron can displace copper from its solution. The iron nail gets coated with a brown layer of copper and the colour of the blue copper sulphate solution changes to pale green." (Q.03-Jul-2022)
This simple experiment demonstrates a fundamental concept in chemistry: the reactivity series of metals, where a more reactive metal can displace a less reactive metal from its salt solution.
Understanding the Reaction
The reaction can be represented by the following word equation:
Iron + Copper Sulphate → Iron Sulphate + Copper
And the simplified chemical equation is:
Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
Here:
Fe(s)represents solid iron (the nail).CuSO₄(aq)represents aqueous copper sulphate solution (the blue liquid).FeSO₄(aq)represents aqueous iron sulphate solution (the pale green liquid).Cu(s)represents solid copper (the brown coating).
This reaction is a classic example of a single displacement reaction. The iron atoms lose electrons and become iron ions (Fe²⁺), which go into the solution, forming iron sulphate. The copper ions (Cu²⁺) from the copper sulphate gain electrons and become neutral copper atoms, which deposit as a solid layer on the iron nail.
This change is easily visible and often used as a demonstration in educational settings to show chemical reactivity.
