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Thermal Decomposition of Lead Nitrate

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Aim

To observe the thermal decomposition of lead nitrate powder.

Materials Required

Lead nitrate powder, Pb(NO₃)₂
Boiling tube
Test tube holder (tongs)
Bunsen burner

Theory

Lead nitrate is a white crystalline solid. When it is strongly heated, it decomposes into yellow solid lead oxide (PbO), brown-colored nitrogen dioxide (NO₂) gas, and oxygen (O₂) gas. Because heat is used to break down the single reactant, this is a thermal decomposition reaction.

Chemical Equation:
2Pb(NO₃)₂ (s) + Heat → 2PbO (s) + 4NO₂ (g) + O₂ (g)

Procedure

  1. Take about 2 g of lead nitrate powder in a boiling tube.
  2. Hold the boiling tube with a test tube holder.
  3. Heat the tube over the flame of a Bunsen burner.
  4. Observe the colour of the solid residue and the gas evolved.

Precautions

Status: Ready
Color: None

Observation Table

S.No. Action Observation

📹 Experiment Video

Knowledge Check

1. What are the thick brown fumes evolved during the heating of lead nitrate?

2. What is the color of the lead oxide (PbO) residue formed?

3. Why is this reaction classified as a thermal decomposition reaction?

4. What is the original color of Lead Nitrate [Pb(NO₃)₂] powder?

5. Which gas (other than NO₂) is also evolved in this reaction?

Lab Report Summary

Experiment: Thermal Decomposition of Lead Nitrate

Aim: To observe the thermal decomposition of lead nitrate powder.

Result:

Lead nitrate (white powder) undergoes thermal decomposition on heating to yield a yellow solid residue of lead oxide (PbO), thick brown fumes of nitrogen dioxide (NO₂), and oxygen gas (O₂).