Andy Benham

The Murder of Roger Ackroyd - S7-E1

Factual error: A few drops of acid are dropped on a penny and the liquid bubbles (colorless liquid) as the acid eats its way through the penny. The penny is mostly copper. Any acid that can react with a copper will also produce a bright green to bright blue solution of dissolved copper, which is not the color seen. (00:05:20)

Noman

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Suggested correction: Not necessarily. It depends on the acid and its strength. A weak acid may only oxidise copper to a monovalent state (Copper (I)) (which is colourless) rather than its divalent (Copper (II)) state which produces the blue solution.

Andy Benham

The acid must be an oxidizing acid. This plus being done in the open air would result in any copper (I) formed quickly being oxidized to copper (II). Copper (I) is extremely unstable under the conditions shown.

Noman