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?Which compounds might have been present?A. Fe(NO3)3B. Al(NO3)3C. Zn(NO3)2D. Bi(NO3)3E. NaNO3F. Cd(NO3)2G. Sn(NO3)4H. Ca(NO3)2

FREE Expert Solution

Given:

A. Fe(NO3)3
B. Al(NO3)3
C. Zn(NO3)2
D. Bi(NO3)3
E. NaNO3
F. Cd(NO3)2
G. Sn(NO3)4
H. Ca(NO3)2

Nitrates (NO3-) are soluble

A. Fe3+
B. Al3+
C. Zn2+
D. Bi3+
E. Na+
F. Cd2+
G. Sn4+
H. Ca2+

Step 1: addition of dilute HCl, no precipitate formed

HCl(aq) → H+(aq) + Cl-(aq)

Cl- are soluble except when paired with Ag+, Pb2+, Cu+, Hg22+

All are possible since all the metals would be soluble with Cl-


Step 2: The pH was lowered to about 1 and H2S was bubbled through the solution. No precipitate formed. 

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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?

Which compounds might have been present?

A. Fe(NO3)3

B. Al(NO3)3

C. Zn(NO3)2

D. Bi(NO3)3

E. NaNO3

F. Cd(NO3)2

G. Sn(NO3)4

H. Ca(NO3)2

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