Zinc and lead are more reactive than copper , hence they displace copper from its componds , how a more reactive element displaces a less reactive one in a reaction , not understand ?

A more reactive metal has a tendency to get oxidized and a less reactive metal ion has a tendency to get reduced. Therefore, a more reactive metal displaces a less reactive metal from its salt solution.For example:
Zn + CuSO4 ZnSO4 + Cu
Here, more reactive metal Zn is oxidized and Cu2+ ion is reduced to Cu metal.

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Consider this example from net. It may be useful to you.

Our Objective

To study a single displacement reaction with the help of iron nails and copper sulphate solution.

The Theory

What is meant by a single displacement reaction?

Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reaction.

Reaction of iron nails with copper sulphate solution.

How is the chemical reactivity of metals linked with their position in the electrochemical series?

Chemical reactivity of metals is linked with their relative positions in the activity series. Certain metals have the capacity to displace some metals from the aqueous solutions of their salts. A metal placed higher in the activity series can displace the metal that occupies a lower position from the aqueous solution of its salt. The displacement reaction is not limited to metals only. Even non-metals can take part in these reactions.

Examples are halogens. The activity series of halogen is F Cl Br I.

Note the point:

An important thing to remember with single displacement reaction is that elements that form cations can only displace cations and elements that form anions can only displace anions.

Classification of single displacement reaction:

  • Cation replacement reaction
  • Anion replacement reaction
  • Cation replacement reactions
  • In this reaction, one cation replaces another one from its solution. A cation is a positively charged ion or metal. All metal displacement reactions are cation replacement reactions. Let us discuss some examples of cation replacement reactions.

    Let us discuss some examples of cation replacement reactions.

    • If a strip of magnesium metal is placed in copper sulphate solution, the blue colour of copper sulphate disappears and the magnesium metal turns brown as the displaced copper is deposited on it. In the reactivity series, the position of magnesium is above that of copper. So it is more reactive than copper and it would displace copper from copper sulphate solution.

    • Also metals like Zn, Al, Pb, Fe, etc., displace Cu from copper salt solution. The chemical reaction can be written as:

    • Iron displaces lead from the aqueous solution of lead nitrate.

    If a less reactive metal is added to a salt solution of more reactive metal, nothing will happen.

    • Similarly, metals above hydrogen in the reactivity series displace hydrogen from dilute acids.

    For example,

    • The metals such as potassium, sodium, lithium, etc. reacts more vigorously with dilute acids forming metal salts and hydrogen gases.

    • Metals such as aluminium, zinc, magnesium, iron, etc., react safely with dilute acids.

    The reaction Zn with dil. H2SO4 is often used in the laboratory for the preparation of hydrogen gas.

  • Anion replacement reaction
  • In this reaction, one anion replaces another one from its solution. An anion is a negatively charged ion or non-metal. For example, more reactive halogen replaces less reactive halogen from its solution.

    • Chlorine displaces bromine from an aqueous solution of sodium bromide.

    • Bromine displaces iodine from potassium iodide solution.

Learning Outcomes
  1. Students acquire good understanding about concepts like single displacement reaction, and cationic replacement reactions.
  2. Students classify the metals that can displace the other metals from salt solutions.
  3. Students develop the skill to demonstrate a single displacement reaction using iron nails and copper sulphate solution.
  4. Students will be able to distinguish a single displacement reaction from a given set of chemical reactions.
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