10 8 phosphate test take 10 drops of the original

10

8. Phosphate test: Take 10 drops of the original test solution (from Step 1) and add
five drops of 6 M HNO
3
and five drops of 0.4 M (NH
4
)
2
MoO
4
. Formation of a
yellow precipitate confirms the presence of phosphate. All the other anions form
a white precipitate.
9. Nitrate test: Add five drops of 1 M FeSO
4
solution to 10 drops of the original test
solution (from Step 1) and mix thoroughly. Add 2-3 drops of 3 M H
2
SO
4
to this
solution until it is acidic. Incline the test tube at a 45° angle and gently add 1 mL
of concentrated H
2
SO
4
using a dropper along the sides of the test tube. Make sure
that the contents of the test tube do not mix. Allow the test tube to stand for a
few minutes and look for the appearance of a brown ring at the interface of the
sulfuric acid layer (the bottom) and the test solution layer. Formation of the
brown ring confirms the presence of nitrate ions in the original solution.
10. Oxalate test: The presence of oxalate in the unknown is determined by exclusion.
If the unknown tests negative to all the above confirmatory tests, then based on
the process of elimination, the unknown must be oxalate.
11

Data Table
P
ART
1: A
NALYSIS OF
K
NOWN
S
AMPLES
Step Experiment Observation
1 Add 6 M nitric acid to a pinch of the
solid carbonate salt
3 Carbonate + 0.1 M BaCl
2
6 Chloride + HNO
3
+ 0.1 M AgNO
3
6 Bromide + HNO
3
+ 0.1 M AgNO
3
6 Iodide + HNO
3
+ 0.1 M AgNO
3
7 Chloride test
8a Bromide test
8b Iodide test
10 Sulfate + 6 M HCl followed by two
drops of 0.1 M BaCl
2
12 Phosphate + five drops of 6 M HNO
3
and five drops of 0.4 M (NH
4
)
2
MoO
4
14 Nitrate + 1 M FeSO
4
+ 3 M H
2
SO
4
+
concentrated H
2
SO
4
12

P
ART
2: A
NALYSIS OF
U
NKNOWN
S
AMPLE
Observations
Step Experiment UNKNOWN 1 UNKNOWN 2 UNKNOWN 3
1 Unknown +
6 M nitric
acid
3 Carbonate
test
5 Halide test
6 Chloride test
7a Bromide test
7b Iodide test
8 Sulfate test
9 Phosphate
test
10 Nitrate test
13

Results
List the relevant observations and the identity of the unknown below:
Unknown
Number
Relevant Observations Identify
Name Formula
1
2
14
3