The aims of the practical are;
• To become familiar with the risk assessment process and safety procedures
that need to be followed before you undertake an experiment
• To re-design an experiment so that others can replicate your methods
1. Grind about 2 g of lawn fertiliser and transfer a small amount into a beaker.
2. Add 50 mL of water.
3. Filter the solution into a 600 mL beaker.
4. Add 3 mL of 2 M HCl and make up to 200 mL total volume.
5. Heat the solution.
6. Slowly add the required amount of 0.5 M BaCl2 while the sample is still hot.
7. Allow the precipitate to settle and the solution to cool.
8. Weigh a sintered glass crucible before using it to filter the solution.
9. Wash with warm water.
10. Test the filtrate with AgNO3. If AgCl forms, discard the filtrate and continue to
wash the precipitate until the filtrate shows no signs of AgCl.
11. Reweigh the sintered glass crucible and calculate the mass of precipitate
12. Calculate the amount of sulfate in the fertiliser and compare to the amounts
quoted by the manufacturer.