A clear liquid was found in a laboratory, and it was desired to know if it could

Question

A clear liquid was found in a laboratory, and it was desired to know if it could be disposed of safely down the drain. It was found to be miscible with water and weakly acidic. Which of the following results is most useful as to determining whether it has silver, mercury, or lead, any of which would require professional disposal?

A. Hydrochloric acid was added, and no precipitate formed.

B. Sodium hydroxide was added, and a white precipitate formed.

C. Potassium chromate was added, and the solution turned yellow.

D. Nitric acid was added, and no precipitate formed.

A. Hydrochloric acid was added, and no precipitate formed.

B. Sodium hydroxide was added, and a white precipitate formed.

C. Potassium chromate was added, and the solution turned yellow.

D. Nitric acid was added, and no precipitate formed.

Explanation / Answer

In general, silver(I), lead(II), and mercury(I) are grouped together in qualitative analysis schemes because they are the only common metal cations that form insoluble precipitates with chloride ion.

so,

option A: Hydrochloric acid was added, and no precipitate formed.

This test clearly confirms that the a clear liquid in a laboratory is free from the above cations and free to dispose.

.

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