A metal strip in a salt solution
"A metal strip in a salt solution" is a free, interactive Class 11 Chemistry simulation for NEET and JEE, built on the lesson "Competitive electron transfer" in Redox Reactions. Choose a metal and a salt solution. Watch the strip and the colour of the solution. The line below places each couple by its standard electrode potential, E°. A metal gives electrons to the ion of any couple placed above its own. So Zn > Fe > Cu > Ag in the tendency to release electrons: this is the activity series. JEE Main asked 16 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Competitive electron transfer in Redox Reactions. Change the values and watch what happens.
In JEE Main
42 shifts analysed
16 questions from Redox Reactions across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §7.2.1
- A zinc strip dipped in copper nitrate solution for about an hour gets a reddish copper coating, and the blue of the solution fades: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s). Zinc loses electrons to Cu²⁺.
- The Zn²⁺ formed can be shown by passing H₂S through the colourless solution after making it ammoniacal: a white precipitate of ZnS appears.
- A copper rod in zinc sulphate solution shows no change, and H₂S gives no black CuS. So Cu does not hand electrons to Zn²⁺; the reverse transfer does not occur.
- Copper in silver nitrate solution does react: the solution turns blue as Cu²⁺ forms and silver is deposited, Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s).
- The tendency to release electrons therefore falls in the order Zn > Cu > Ag. Arranging metals by this competition for electrons gives the metal activity series (electrochemical series).
- In some pairs neither side wins completely. Cobalt in nickel sulphate solution reaches a state where both Co²⁺ and Ni²⁺ are present at moderate concentrations: the reaction reaches equilibrium.
- The same competition, when the two half reactions are kept in separate beakers joined by a wire, can drive an electric current. This is the basis of a galvanic cell.
Questions
3 answers
- What does the "A metal strip in a salt solution" simulation show?
- Choose a metal and a salt solution. Watch the strip and the colour of the solution. The line below places each couple by its standard electrode potential, E°.
- Does JEE Main ask questions from Redox Reactions?
- Yes. JEE Main asked 16 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Competitive electron transfer" in Redox Reactions (Class 11 Chemistry).
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