Activity 5.7 – Displacement Reaction (Fe + CuSO4)

Aim

• Illustrate a single displacement reaction using iron and copper sulphate.

Materials

• $\approx$ 1 teaspoon $CuSO_4$ (blue vitriol)
• $\approx$ half-cup water
• Few drops dilute $H<em>2SO</em>4$ (to prevent hydrolysis, keeps solution clear)
• Clean iron nail(s) / iron scrap
• Glass tumbler / beaker, thread (to suspend nail)

Procedure (Activity 5.7)

• Dissolve $CuSO_4$ in water inside the tumbler.
• Add few drops of dilute $H<em>2SO</em>4$.
• Suspend a cleaned iron nail completely in the solution.
• Leave undisturbed for $\text{30–60 min}$.

Observations

• Solution’s blue colour gradually fades / turns light green.
• Brownish-reddish layer appears on iron nail surface.

Inference

• Iron displaces copper from $CuSO_4$, depositing metallic $Cu$ on the nail.
• Fading of blue colour indicates formation of $FeSO_4$ in solution.

Chemical Equation

• $CuSO<em>4(aq) + Fe(s) \rightarrow FeSO</em>4(aq) + Cu(s)$

Key Concepts

• Single displacement (replacement) reaction: a more reactive metal (Fe) replaces a less reactive metal (Cu) from its salt solution.
• Reactivity series: $Fe$ lies above $Cu$, hence displacement is feasible.
• Colour changes act as visual evidence of chemical change.