What are the reasons for the unreactivity of nitrogen gas (N2)?

Nitrogen gas (N2) is unreactive due to two main factors:

  1. Strong triple covalent bond: The two nitrogen atoms in N2 are held together by a strong triple covalent bond. Breaking this bond requires extreme conditions, making nitrogen gas unreactive under normal circumstances.
  2. Non-polar nature: N2 is a non-polar molecule, meaning it has an even distribution of charge. This non-polarity makes it difficult for nitrogen gas to form compounds with other elements.

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Explain, with the use of an equation, why ammonia is classed as a Brønsted-Lowry base.

Ammonia (NH3) is a Brønsted-Lowry base because it can accept a proton (H+) from an acid to form the ammonium ion (NH4+).

NH3(aq) + H+(aq) ➔ NH4+(aq)

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Explain, with the use of an equation, why an aqueous solution of ammonia is only weakly alkaline.

An aqueous solution of ammonia undergoes an equilibrium reaction with water: 

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

The position of equilibrium lies well over to the left so the concentration of OH- ions is low.

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Why is the reaction between ammonium chloride and calcium hydroxide classed as an acid-base reaction?

The reaction between ammonium chloride and calcium hydroxide is an acid-base reaction because:

  1. The ammonium ion (NH4+) from NH4Cl acts as a Brønsted-Lowry acid by donating a proton (H+).
  2. The hydroxide ion (OH-) from Ca(OH)2 acts as a Brønsted-Lowry base by accepting the proton (H+) donated by NH4+.


The overall reaction can be represented as: NH4+(aq) + OH-(aq) ➔ NH3(aq) + H2O(l)

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Describe and explain how a compound is tested for the presence of ammonium ions.

If the compound contains ammonium ions, it will give off ammonia when heated with a base. Ammonia is the only common alkaline gas so it will turn damp red litmus paper blue.

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Why is the reaction between ammonium chloride and calcium hydroxide classed as a displacement reaction?

Because calcium displaces ammonia from its salt, resulting in the formation of calcium chloride, ammonia (and water).

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What is the equation, including state symbols, for the reaction between ammonium chloride, NH4Cl, and calcium hydroxide, Ca(OH)2?

2NH4Cl(s) + Ca(OH)2(s) ➔ CaCl2(s) + 2H2O(l) + 2NH3(g)

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