Problem: 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?a) Ca(NO3)2b) AgNO3c) Fe(NO3)3d) Cr(NO3)3e) Cu(NO3)2f) Bi(NO3)3g) Co(NO3)2h) KNO3

FREE Expert Solution

a) Addition of HCl: precipitates Ag+, Pb2+, or Hg22+

No precipitate = rule out AgNO3

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Problem Details

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?

a) Ca(NO3)2

b) AgNO3

c) Fe(NO3)3

d) Cr(NO3)3

e) Cu(NO3)2

f) Bi(NO3)3

g) Co(NO3)2

h) KNO3

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