Sulfate Experiment

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:

Easychem - Sulfate Experiment