Monitoring and Management> 3. Manufactured Products >
Identify data, plan, select equipment and perform first-hand investigations to measure the sulfate content of lawn fertiliser and explain the chemistry involved
- Gravimetric Analysis: A method of quantitative analysis that involves the precipitation of a highly insoluble compound followed by weighing of the dried precipitate formed.
- Gravimetric analysis can be used to determine the sulfate content of a lawn fertiliser.
- Barium sulfate is a highly insoluble sulfate compound, and can be formed by adding barium chloride to sulfate in solution:
- The sulfate content of a lawn fertiliser can be determined using the following procedure:
- Grind a sample of fertiliser into a fine powder using a mortar and pestle.
- Place a certain mass (around 1 g) of the ground fertiliser into a certain volume (around 100 mL) of a known concentration (around 0.1 M) of dilute hydrochloric acid.
- Stir to dissolve as much solid a possible.
- Filter off insoluble material.
- Slowly add excess barium chloride solution to the filtrate to form barium sulfate precipitate.
- Weigh a dry filter paper, and then filter off the precipitate.
- Dry the filter paper and then weigh again to determine the mass of the precipitate.
- Determine the mass of sulfate:
- Determine the percentage of sulfate in the fertiliser:
