Nitrogen Chemistry

Question 1

Describe the bonding in an ammonium ion (NH₄⁺).

Answer 1

The N atom forms 3 covalent bonds by sharing one of its valence electrons with each of the 3 H atoms. A single dative covalent bond also forms when the nitrogen atom in an ammonia molecule donates a pair of electrons to a proton (H⁺).

Question 2

Describe a test you could use to determine whether a solution contains ammonium ions (NH₄⁺).

Answer 2

• Ammonium ions can be tested for by adding sodium hydroxide to the solution and gently heating the mixture.
• If ammonium ions are present, they will react with the hydroxide ions and ammonia gas will be evolved.
• Ammonia gas is alkaline, so its identity can be confirmed using a damp piece of red litmus paper.
• If present, the paper will turn blue.

Question 3

Write a balanced equation for the reaction of nitrate(III) ions (NO₂⁻) and water to form nitrate(V) ions (NO₃⁻).

Answer 3

2NO₂⁻ + H₂O → NO₃⁻ + 2H⁺ + 2e⁻

Question 4

During lightning storms, nitrogen and oxygen in the air can react to form nitrogen monoxide.
Write an equation for this reaction.
[1 mark]

Answer 4

N₂ + O₂ → 2NO

Question 5

Nitrogen monoxide reacts further with oxygen to form nitrogen dioxide. What would you see during this reaction?
[1 mark]

Answer 5

A brown colour would appear since nitrogen dioxide is brown.