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3.2 Use of amount of substance in relation to masses of pure substances

3.2 Use of amount of substance in relation to masses of pure substances

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Question 10

An agricultural scientist investigated the total dissolved solids (TDS) in a runoff sample collected from a commercial hydroponic greenhouse.

The scientist used the following procedure:

  1. Filter the runoff sample to remove any suspended organic debris.
  2. Record the mass of a clean, dry porcelain crucible.
  3. Pipette exactly 40 cm3 of the filtered runoff into the crucible.
  4. Heat the crucible gently using a Bunsen burner until all the liquid has evaporated to dryness.
  5. Re-weigh the crucible and the remaining dry mineral salts.

The recorded measurements are shown in the table below:

MeasurementMass (g)
Mass of empty crucible54.32
Mass of crucible and dry mineral salts54.58

Calculate the concentration of dissolved mineral salts in g dm−3\text{g dm}^{-3}g dm−3 (mass in 1000 cm3) of this runoff sample.

[3]
Markscheme

3.2 Use of amount of substance in relation to masses of pure substances Questions

  1. GCSE
  2. /Chemistry
  3. /3.2 Use of amount of substance in relation to masses of pure substances

38 exam-style questions on AQA GCSE Chemistry 3.2 Use of amount of substance in relation to masses of pure substances, covering 3.2.1 Moles (HT only), 3.2.2 Amounts of substances in equations (HT only), 3.2.3 Using moles to balance equations (HT only), 3.2.4 Limiting reactants (HT only), and 3.2.5 Concentration of solutions. Each one has a worked solution and a mark scheme showing where the marks go.

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