Question

Write balanced chemical equation for the following statements and state the colour changes you observe.

i) Iron nail is kept immersed in copper sulphate solution.
ii) Potassium iodide solution is added to lead nitrate solution.

Answer 1

i) Fe + CuSO4 -> FeSO4 + Cu

Color changes:

• Initially, iron nail is metallic gray.
• Copper sulfate solution is blue.
• After reaction, the iron nail becomes coated with reddish-brown copper, and the blue color of the copper sulfate solution fades.

ii) 2KI + Pb(NO3)2 -> 2KNO3 + PbI2

Color changes:

• Potassium iodide solution is colorless.
• Lead nitrate solution is colorless.
• After the reaction, a bright yellow precipitate of lead iodide (PbI2) forms, indicating the color change.