Noman

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

Dumb Witness - S6-E4

Factual error: Spoiler. Police Sergeant Keeley tells Poirot that Doctor Grainger died of carbon monoxide poisoning. The killer turned the natural gas in the bedroom and did not light the heater. This would result in the room filling with natural gas, not carbon monoxide. (01:17:30)

Noman

Upvote valid corrections to help move entries into the corrections section.

Suggested correction: Surely it was coal gas at that time, before we all converted to natural gas?

The product of coal gas is still methane, which is CH4. It may contain tiny volumes of CO but the gas asphyxiation would still have come from methane, not carbon monoxide.

The Yellow Iris - S5-E3

Factual error: Poirot smells and very carefully tastes a drink and says, "Potassium cyanide." It is impossible to distinguish between potassium cyanide and sodium cyanide (the other common cyanide) by this method. In addition, there are another less common cyanides that would smell and taste the same as potassium cyanide. (00:16:01)

Noman

The Underdog - S5-E2

Factual error: Lily looks over part of the procedure for the manufacture of Astroprene. There are several problems with the chemical structures shown in step two of the procedure. This step appears to be a simple acid catalyzed rearrangement of the molecule shown. The procedure should begin with a C inside the hexagonal ring and end with the C outside the ring with no other changes. The errors include, among other things, a carbon atom at the lower left of the ring with two lines (bonds) to it. The C should have four bonds (lines), the two shown plus two to hydrogen atoms (H). The bonds to H may be condensed so the C will look something like -CH2 - (the 2 would be a subscript). (00:10:30)

Noman

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