A student was given a solid containing a mixture of nitrate salts. The sample completely dissolved in water, and upon addition of dilute HCl, no precipitate formed. The pH was lowered to about 1 and H2S was bubbled through the solution. No precipitate formed. The pH was adjusted to 8 and H2S was again bubbled in. This time, a precipitate formed. Which compounds might have been present in the unknown? The list to choose from: Cr (NO3) 3 Co (NO3) 2 NaNO3 Ni (NO3) 2 Bi (NO3) 3 Ca (NO3) 2 Sn (NO3) 4 Cd (NO3) 2

Question

Anne Schaefer

Chemistry

2 April, 10:19

A student was given a solid containing a mixture of nitrate salts. The sample completely dissolved in water, and upon addition of dilute HCl, no precipitate formed. The pH was lowered to about 1 and H2S was bubbled through the solution. No precipitate formed. The pH was adjusted to 8 and H2S was again bubbled in. This time, a precipitate formed. Which compounds might have been present in the unknown? The list to choose from: Cr (NO3) 3 Co (NO3) 2 NaNO3 Ni (NO3) 2 Bi (NO3) 3 Ca (NO3) 2 Sn (NO3) 4 Cd (NO3) 2

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Marcel Callahan · Answer 1

The nitrates of Bi, Sn and Cd is ruled out because their sulfides are insoluble in acidic medium.

Nitrates of Ni or Co may be present because their sulfides are insoluble in basic medium. The presence of other nitrates are ruled out.