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Related Topic: Nitrogen and its Compounds

Related Subtopic: Laboratory preparation of nitric (V) acid



Questions 4.5.1

  1. Write the chemical formula of nitric (V) acid.
  2. Identify the negative and positive ions in nitric (V) acid.
  3. Name the class of salts which have the same negative ions as in nitric (V) acid.
  4. Name the class of compounds which have hydrogen ions.
  5. Identify two substances you can react together to produce nitric (V) acid in the laboratory.
  6. Write an equation for laboratory preparation of pure nitric (V) acid (not mixed with water).
  7. In this method, heating is required and nitric (V) acid is produced as a vapour. Explain how you would change the vapour into liquid (V) nitric acid.
  8. Draw a possible set-up you would use to prepare nitric (V) acid in the laboratory. Heating is required.

    9. NB: Pure nitric (V) acid is colourless. However, due to heating, some nitric (V) acid thermally decomposes into water, oxygen and nitrogen (IV) oxide. Nitrogen (IV) oxide dissolves in the rest of the acid, causing it appear yellow. The yellow coloration can be removed by bubbling air through the mixture.


  9. Suggest a reason why concentrated sulphuric (VI) acid is more suitable than concentrated hydrochloric acid in preparing nitric (V) acid.


Answers to Questions 4.5.1


  1. HNO3
  2. Nitrate ions (negative) and hydrogen ions (positive)
  3. Nitrates
  4. Acids
  5. Potassium nitrate and concentrated suplhuric acid.
  6. KNO3(s) + H2SO4(l) → KHSO4(s) + HNO3(g)
  7. Condense the vapour by cooling it under ice water. The vapour should not mix with water.
  8. Set-up for preparing nitric (V) acid in the laboratory,nitrogen and its compounds,high school chemistry

    Plate 4.5.1(b)Answers to Questions 4.5.3 No 8 (Set-up for preparing nitric (V) acid in the laboratory)

  9. 4HNO3(g) → 2H2O(g) + 4NO2(g) + O2(g)
  10. Concentrated hydrochloric acid is volatile; so it would escape as hydrogenchloride during heating. Morover, it would contaminate any nitric (V) acid produced.