Question 2

2.1 Ammonia NH3(g) and hypochlorous acid HOCℓ(ℓ) are both examples of
covalent compounds.

2.1.1 Define the term bonding pair. (2)

2.1.2 Draw Lewis structures for the following molecules:

(a) NH₃ (2)
(b) HOCℓ (2)

2.1.3 Write down the:

(a) Number of bonding pairs in NH3 (1)
(b) Number of lone pairs on the oxygen atom in HOCℓ (1)
(c) Shape of an ammonia molecule (1)

2.1.4 Which bond, N-H or O-H, is more polar? Give a reason for the
answer. (2)

2.1.5 Write down the type of intermolecular forces present in BOTH
ammonia and hypochlorous acid. (1)

2.1.6 When ammonia dissolves in water, the ammonium ion is
formed.
What type of bond forms between the ammonia molecule and the
hydrogen ion? (1)

2.2 The graph of potential energy versus distance between the nuclei of two
oxygen atoms during bond formation is shown below.

• 

2.2.1 Define the term bond energy. (2)

2.2.2 Which curve, A or B, represents the formation of the double bond (O=O)
between oxygen atoms? Briefly explain the answer. (3)

2.2.3 Write down the bond length of the bond represented by curve B. (1)

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