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Which will not act as a ligand in the formation of a complex ion? A CH₄ B CO C H₂O D NH₃ - AQA - A-Level Chemistry - Question 18 - 2020 - Paper 3
Question 18
Which will not act as a ligand in the formation of a complex ion? A CH₄ B CO C H₂O D NH₃
Worked Solution & Example Answer:Which will not act as a ligand in the formation of a complex ion? A CH₄ B CO C H₂O D NH₃ - AQA - A-Level Chemistry - Question 18 - 2020 - Paper 3
Step 1
Which will not act as a ligand in the formation of a complex ion?
Answer
To determine which molecule does not act as a ligand in the formation of a complex ion, we need to evaluate the ability of each molecule to donate electron pairs.
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CH₄ (Methane): This molecule has no lone pairs on the carbon atom and is generally a non-polar molecule. It cannot act as a ligand because it cannot donate an electron pair.
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CO (Carbon Monoxide): CO is known to be a strong field ligand due to its ability to donate a lone pair of electrons, forming stable complexes with metal ions.
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H₂O (Water): Water can act as a ligand by donating a lone pair from the oxygen atom, thus forming complex ions with various metal ions.
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NH₃ (Ammonia): Ammonia is also a well-known ligand; it possesses a lone pair on the nitrogen atom that it can donate to form complexes with metal ions.
Given this analysis, the correct answer is A CH₄, as it does not have the necessary structure to function as a ligand in complex ion formation.