Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Making sodium, potassium and ammonium salts
18 practice questions
Practice questions
11–18 of 18
Question 11
3 marks · Normal
Answer and see the solution →Explain the role of methyl orange indicator in an acid–alkali titration to prepare a sodium salt. Why does the indicator colour change at the endpoint, and how does this help determine when the reaction is complete?
Question 12
4 marks · Normal
Answer and see the solution →A student tries to make sodium nitrate by mixing sodium hydroxide and nitric acid using the traditional 'add excess solid, then filter' method. The table shows the solubility of sodium nitrate, sodium sulfate and copper(II) sulfate in water:
Salt Solubility in water at room temperature (g/100g water) Sodium nitrate 92 Sodium sulfate 21 Copper(II) sulfate 23 Use the data to explain why the excess solid method does not work for making sodium nitrate, and how this relates to the need for titration.
Question 13
1 mark · Normal
Answer and check →Which step must be repeated without indicator when preparing pure potassium sulfate crystals by titration?
- A.Mixing the identified volumes of acid and alkali
- B.Adding more indicator to the solution
- C.Heating the reaction mixture directly after titration
- D.Filtering the solution before adding acid
Question 14
2 marks · Normal
Answer and see the solution →Write the balanced chemical equation for preparing sodium chloride from sodium hydroxide and hydrochloric acid. Name the type of reaction that takes place.
Question 15
4 marks · Normal
Answer and see the solution →When using methyl orange during an acid–alkali titration:
(a)[1 mark]State the colour of methyl orange in an alkaline solution.
(b)[2 marks]Describe what you would observe as acid is slowly added to the alkaline solution containing methyl orange.
(c)[1 mark]Explain why methyl orange is suitable for titrations involving strong acids and strong alkalis.
Question 16
2 marks · Hard
Answer and see the solution →Explain why methyl orange is a suitable indicator for titrations involving sodium hydroxide and hydrochloric acid. In your answer, mention what the colour change shows about the reaction mixture.
Question 17
5 marks · Hard
Answer and see the solution →A student is asked to prepare pure ammonium sulfate crystals using ammonia solution and dilute sulfuric acid in the laboratory.
(a)[2 marks]Explain why the titration method must be used instead of the excess solid method for this preparation.
(b)[2 marks]State two practical reasons why an indicator is not added to the acid and alkali mixture when making the final batch of ammonium sulfate for crystallisation.
(c)[1 mark]Describe what the student should do after mixing the correct volumes of acid and alkali, to obtain pure, dry crystals of ammonium sulfate.
Question 18
2 marks · Hard
Answer and see the solution →Give two steps the student must follow to make pure potassium chloride crystals using titration and crystallisation with potassium hydroxide and hydrochloric acid.