Which compound forms a white precipitate when added to aqueous silver nitrate? A bromoethane B ethanal C ethanoic anhydride D ethanoyl chloride - AQA - A-Level Chemistry - Question 28 - 2021 - Paper 3

To determine which compound forms a white precipitate with aqueous silver nitrate, we need to consider the reaction of silver nitrate with different functional groups. Silver nitrate reacts with halides and certain carbonyl compounds to form precipitates.

1. Bromoethane (A): This is an alkyl halide, and it will react with silver nitrate to form silver bromide (AgBr), which is a white precipitate.

2. Ethanal (B): Ethanal is an aldehyde and will not form a precipitate with silver nitrate under standard conditions.

3. Ethanoic Anhydride (C): This compound does not contain a suitable halogen or carbonyl that would react to form a precipitate with silver nitrate.

4. Ethanoyl Chloride (D): This is an acyl chloride that does not produce a solid precipitate when reacted with silver nitrate; instead, it forms silver chloride (AgCl) when containing suitable oligomers.

Thus, among these options, the correct answer is ethanoyl chloride (D) as it leads to the formation of a precipitate.