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A student took iron nails and dipped them in solution 'X' for twenty minutes. After some time he noticed that the colour of the iron nails became brownish. Identify solution 'X' in which the nail was dipped.
Iron sulphate
Copper sulphate
Lead sulphate
Zinc sulphate
Copper sulphate
The student has observed a displacement reaction. When iron nails are dipped in a copper sulphate solution, the iron (being more reactive) displaces the copper from the solution, forming iron sulphate and depositing metallic copper on the nails, which gives them a brownish appearance.
The student has observed a displacement reaction. When iron nails are dipped in a copper sulphate solution, the iron (being more reactive) displaces the copper from the solution, forming iron sulphate and depositing metallic copper on the nails, which gives them a brownish appearance.
Think of it like a stronger teammate 'kicking out' a weaker player from their spot on a team; here, Iron is the stronger player who pushes Copper out of the 'Sulphate' team.
Fe(s)+CuSO4тАЛ(aq)тЖТFeSO4тАЛ(aq)+Cu(s) тАФ Chemical equation of the displacement reaction
The principle behind this is the reactivity series of metals. Iron (Fe) is more reactive than copper (Cu), so it displaces copper ions from the blue copper sulphate solution (CuSO4тАЛ). The chemical equation is: Fe(s)+CuSO4тАЛ(aq)тЖТFeSO4тАЛ(aq)+Cu(s). The blue color of the solution eventually fades to light green due to the formation of iron(II) sulphate, and the reddish-brown deposit on the nail is solid copper.
The initial solution of Copper Sulphate is blue in color.
Iron replaces copper because it is higher in the reactivity series.
The brownish deposit on the nail is elemental Copper.
The solution changes from blue to light green as Iron(II) Sulphate is formed.
Used to demonstrate reactivity series in chemistry labs
Fundamental principle in extractive metallurgy
Copper sulphate is a common salt used in school experiments.
Option A is incorrect as Iron does not react with Iron Sulphate.
Option C and D are incorrect as Iron is not reactive enough to displace Lead or Zinc.
B is correct тАФ The brownish color on the iron nail is due to the deposition of copper metal through a displacement reaction in the copper sulphate solution.
Remember: A more reactive metal always displaces a less reactive metal from its salt solution. Check the reactivity series (K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au) to predict these reactions.
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