Students may well be aware of how solids and liquids can form a reaction and chemistry experiments are full of examples. This simple demonstration shows how a reaction can take place between two solids; lead nitrate and potassium iodide.
Equipment typically required (per demonstration):
The two chemicals are mixed in equal quantities by putting 15g of each into the small glass jar and shaken vigorously. The amounts must be equal to achieve the desired reaction.
- Glass screw top jar
- Lead nitrate 15g (TOXIC and DANGEROUS FOR THE ENVIRONMENT)
- Potassium iodide 15g (LOW HAZARD)
- Accurate balance
- 2 weighing boats
- 2 spatula
Before reaction, both solids are white. When shaken, lead iodide is formed which is a yellow colour. If the same mixture is placed in a beaker with a few drops of water the reaction occurs much faster. The added water allows the particles of the reactants to meet each other much more quickly.
After the demonstration, the lead iodide must be disposed of in the correct manner. Seek advice if in doubt.
The chemical equation for this reaction is:
Pb(NO3)22KNO (s) + 2KI(s) → 3(s) + PbI2(s)
Typical technician preparation time: 10 minutes
Typical demonstration time: 5 minutes