Aim
To observe the double displacement reaction between lead nitrate and potassium iodide and identify the precipitate formed.
Materials Required
- Lead Nitrate [Pb(NO₃)₂] solution
- Potassium Iodide [KI] solution
- Two test tubes
- Test tube stand
Theory
When an aqueous solution of lead nitrate is mixed with an aqueous solution of potassium iodide, an exchange of ions takes place. This type of reaction is known as a double displacement reaction.
The lead ions (Pb²⁺) combine with iodide ions (I⁻) to form an insoluble solid compound called Lead Iodide, which appears as a striking yellow precipitate.
Procedure
- Take about 5 mL of lead nitrate solution in a clean test tube. (It is a colourless solution).
- Take about 5 mL of potassium iodide solution in another test tube. (It is also colourless).
- Carefully pour the potassium iodide solution into the test tube containing lead nitrate.
- Observe the immediate formation of a vibrant yellow precipitate.
Precautions
- Handle lead salts with care as they are toxic. Wash hands thoroughly after the experiment.
- Use clean test tubes to avoid contamination.
- Do not taste or touch the chemicals directly.
Observation Table
| S.No. | Reactants | Observation | Inference (Product) |
|---|
Knowledge Check
1. What is the colour of the precipitate formed when lead nitrate reacts with potassium iodide?
2. The yellow precipitate is chemically known as:
3. This reaction is a classic example of:
4. What is the physical state of lead nitrate and potassium iodide before mixing?
5. The other product formed, potassium nitrate, remains in which state?
Lab Report
Recorded Observations
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Result
A yellow precipitate of lead iodide (PbI₂) is formed due to the double displacement reaction between lead nitrate and potassium iodide.