When copper reacts with iron sulphate, no reaction occurs, and consequently, no observable change will take place. This is because copper is less reactive than iron and cannot displace iron from its salt solution.
Understanding the Lack of Reaction
The interaction between metals and salt solutions is governed by their relative positions in the metal reactivity series. A displacement reaction, where one metal replaces another in a compound, can only happen if the incoming metal is more reactive than the metal it is attempting to displace.
In the case of copper and iron sulphate:
- Iron (Fe) is a more reactive metal.
- Copper (Cu) is a less reactive metal.
Because copper is less reactive than iron, it does not have the chemical potential to displace iron from iron sulphate (FeSO₄) solution. Therefore, when a piece of copper metal is placed in iron sulphate solution, no change will be observed; the copper will remain unchanged, and the iron sulphate solution will retain its original properties.
The Metal Reactivity Series
The reactivity series, also known as the activity series, lists metals in order of their decreasing reactivity. Metals higher up in the series are more reactive and can displace metals lower down from their salt solutions.
Here's a simplified excerpt showing the relevant metals:
| Metal | Reactivity Level | Example Reaction (with a less reactive metal's salt) |
|---|---|---|
| Potassium | Very High | Displaces almost all metals |
| Sodium | Very High | Displaces almost all metals |
| Calcium | High | Displaces almost all metals |
| Magnesium | High | Displaces almost all metals |
| Aluminium | High | Displaces almost all metals |
| Zinc | Moderate | Displaces iron, lead, copper, silver |
| Iron | Moderate | Displaces lead, copper, silver |
| Lead | Low | Displaces copper, silver |
| Copper | Low | Does not displace iron, lead, zinc |
| Silver | Very Low | Displaces none of the above |
| Gold | Very Low | Extremely unreactive |
- Note: Hydrogen is often included in the series as a reference point for non-metals. For a comprehensive series, you can refer to reliable chemistry resources{:target="_blank" rel="noopener noreferrer"}.
What is a Displacement Reaction?
A displacement reaction is a type of chemical reaction where a more reactive element displaces a less reactive element from its compound.
The general form of a single displacement reaction is:
A + BC → AC + B
Where 'A' is a more reactive metal, and 'B' is a less reactive metal in the compound 'BC'.
Example of a Reaction that Would Occur:
If we were to place a more reactive metal, such as zinc, into copper sulphate solution, a reaction would occur:
Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)
In this case:
- Zinc is more reactive than copper.
- Zinc displaces copper from copper sulphate.
- You would observe the deposition of reddish-brown copper metal and the fading of the blue copper sulphate solution as zinc sulphate (which is colorless) is formed.
Conclusion
In summary, the principle of the reactivity series dictates that a less reactive metal cannot displace a more reactive metal from its salt solution. Since copper is less reactive than iron, no chemical reaction or observable change will occur when copper is placed in iron sulphate solution.
