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3 Quantitative chemistry

3 Quantitative chemistry

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Question 1

Barium sulfate is an insoluble salt used as a radiocontrast agent. It is produced by the reaction between barium chloride solution and sodium sulfate solution:

BaCl2(aq)+Na2SO4(aq)→BaSO4(s)+2NaCl(aq) \text{BaCl}_2\text{(aq)} + \text{Na}_2\text{SO}_4\text{(aq)} \rightarrow \text{BaSO}_4\text{(s)} + 2\text{NaCl(aq)} BaCl2​(aq)+Na2​SO4​(aq)→BaSO4​(s)+2NaCl(aq)

A student investigated the law of conservation of mass using the following method:

  1. Pour barium chloride solution into beaker A.
  2. Pour sodium sulfate solution into beaker B.
  3. Measure the masses of both beakers and their contents.
  4. Pour the solution from beaker B into beaker A.
  5. Measure the masses of both beakers and their contents again.

The table below shows the student's results:

Mass before mixing (g)Mass after mixing (g)
Beaker A and contents85.34120.45
Beaker B and contents80.2545.14
a.

Explain how the results demonstrate the law of conservation of mass. You must use data from the table in your answer.

[3]
b.

Calculate the percentage atom economy for the production of barium sulfate (BaSO4\text{BaSO}_4BaSO4​) in this reaction. Give your answer to 3 significant figures.

Relative formula masses (MrM_{\text{r}}Mr​): BaCl2=208\text{BaCl}_2 = 208BaCl2​=208, Na2SO4=142\text{Na}_2\text{SO}_4 = 142Na2​SO4​=142, BaSO4=233\text{BaSO}_4 = 233BaSO4​=233, NaCl=58.5\text{NaCl} = 58.5NaCl=58.5

[3]
Markscheme

3 Quantitative chemistry Questions

  1. GCSE
  2. /Chemistry
  3. /3 Quantitative chemistry

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