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3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations

3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations

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Question 21

A geochemist investigated the mass of dissolved mineral solids in a sample of geothermal brine from a volcanic well.

The geochemist used the following method:

  1. Measure 50 cm350\text{ cm}^350 cm3 of the geothermal brine sample.
  2. Heat the sample in an evaporating basin until all the water has evaporated.
  3. Measure the mass of the dry mineral residue that remains.
  4. Repeat the experiment three more times.

Table 1

SampleMass of solid residue (g\text{g}g)
11.42
21.39
31.45
41.34
a.

Calculate the mean mass of the solid residue.

[2]
b.

A 300 cm3300\text{ cm}^3300 cm3 sample of geothermal brine from a different well was found to contain 2.46 g2.46\text{ g}2.46 g of dissolved solids. Calculate the mass of dissolved solids in 1000 cm31000\text{ cm}^31000 cm3 of this brine.

[3]
Markscheme

3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations Questions

  1. GCSE
  2. /Chemistry
  3. /3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations

53 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.

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