What is displacement reaction involving metals?

Short Answer:

A displacement reaction involving metals occurs when a more reactive metal displaces a less reactive metal from its compound. In this reaction, the more reactive metal replaces the less reactive metal in a salt, producing a new metal and a new compound.

For example, when zinc is placed in copper sulfate solution, zinc displaces copper to form zinc sulfate and copper metal. Displacement reactions are important for extracting metals and understanding metal reactivity in chemistry.

Detailed Explanation:

Displacement Reaction Involving Metals

Displacement reactions occur when a more reactive metal takes the place of a less reactive metal in a compound. These reactions are based on the reactivity series of metals, which ranks metals according to their tendency to lose electrons and form positive ions.

General Reaction

The general formula for a metal displacement reaction is:
More reactive metal + Compound of less reactive metal → Compound of more reactive metal + Less reactive metal

Example:

  • Zinc and Copper Sulfate: Zn + CuSO₄ → ZnSO₄ + Cu
    • Zinc is more reactive than copper.
    • Zinc displaces copper from copper sulfate to form zinc sulfate and copper metal.

Characteristics of Displacement Reactions

  1. Depend on Reactivity:
    • Only a metal higher in the reactivity series can displace a metal lower in the series.
    • Less reactive metals cannot displace more reactive metals.
  2. Formation of New Compounds:
    • The displaced metal comes out of the solution or compound in its elemental form.
    • A new salt or compound is formed with the more reactive metal.
  3. Observable Changes:
    • Color change in the solution is common. For example, blue copper sulfate solution turns colorless when zinc displaces copper.
    • Precipitation of the displaced metal may be observed.

Examples of Displacement Reactions

  1. Zinc and Copper Sulfate: Zn + CuSO₄ → ZnSO₄ + Cu
  2. Iron and Copper Sulfate: Fe + CuSO₄ → FeSO₄ + Cu
  3. Magnesium and Zinc Sulfate: Mg + ZnSO₄ → MgSO₄ + Zn

Importance of Displacement Reactions

  1. Extraction of Metals:
    • Displacement reactions are used to extract metals from their compounds.
    • For example, more reactive metals like aluminum are used to displace less reactive metals like iron from their ores.
  2. Understanding Reactivity Series:
    • These reactions help in studying the reactivity of different metals and predicting chemical behavior.
  3. Industrial Applications:
    • Used in refining metals and in chemical manufacturing processes where one metal is replaced by another.

Safety and Observations

  • Displacement reactions are generally safe in laboratories if proper precautions are taken.
  • Protective gear should be worn when handling metal salts and reactive metals.
Conclusion:

A displacement reaction involving metals happens when a more reactive metal displaces a less reactive metal from its compound, forming a new metal and a new compound. These reactions are guided by the reactivity series, are useful in extracting metals, and help in understanding the chemical behavior of metals in practical and industrial applications.