Analysis of salt

Question 1

SA + NAOH
What is the analytical Signal?
Presence of ?

Answer 1

Ammonia gas

NH4+ Ions

Question 2

SA + CO3 2-
What is the analytical Signal?
Presence of ?

Answer 2

Co2 gas

Carbonate

Question 3

SA + HCL
What is the analytical Signal?
Presence of ?

Answer 3

White precipitate
Group 1 cations
Ag+ PBb2+ Hg2+

Question 4

Analysis of Group 1 Cations (Ag+
, Hg2 2+
, Pb2+
)

Answer 4

1.Centrifuge the mixture from Step c in order to completely separate the solid precipitate from the
solution. Make sure that you balance the centrifuge before you start.
2. Add one more drop of HCl to ensure that the precipitation is complete. If more precipitate is observed
then centrifuge the mixture again.
3. Decant the supernatant solution into another small test tube and save the precipitate for further study.
The supernatant solution may be discarded in the lab waste container.

Question 5

Separation of Pb2+ from Hg2

2+ and Ag+

Answer 5

1. Wash the precipitate formed to remove contaminants that may be trapped within the solid. This can be accomplished by adding 1.0 mL of deionized water, stirring, and then centrifuging. Once again decant the
   supernatant solution into a small test tube. Save the precipitate and discard the supernatant solution.
2. Prepare a hot water bath by adding tap water to a 250 mL beaker. Add water until the beaker is about one half full. Assemble a stand, ring clamp and wire gauze to heat the water over the Bunsen burner until it is boiling.
   Add 2.0 mL of deionized water to the test tube containing the clean precipitate and place it in the hot water
   bath. Periodically stir the mixture in the test tube for 3-4 minutes.
3. Remove the test tube from the hot water bath and immediately centrifuge the hot mixture. Carefully decant the hot supernatant solution into another small test tube. Save both the precipitate and the supernatant
   solutions for further study.
4. In order to confirm the presence of Pb2+
   , add 1 drop of 6M HC2H3O2
   (ethanoic acid) to the supernatant
   solution obtained. Next add 3-4 drops of 1 M K2CrO4. The formation of a bright yellow precipitate is
   confirmation of the presence of the Pb2+
   ion.

Question 6

Separation and Identification of Hg2

2+

Answer 6

1. Add 10-12 drops of 6 M NH3 to the precipitate from Step 3, and mix thoroughly with your stirring rod.
2. The appearance of a gray solid is confirmation of the presence of Hg2
   2+. Centrifuge the mixture and decant the
   supernatant solution into another small test tube. Save the supernatant solution since it now contains silver in
   the form of the aqueous Ag (NH3)
   2+
   ion.

Question 7

Pb2+ (group two cations)

Answer 7

Bright yellow orange precipitate

Question 8

Bi 2+ group two cations

Answer 8

Jet black precipitate confirms presence o bismuth

Question 9

Cu2+(group two cations)

Answer 9

Blue color of solution

Question 10

Group 2

Group 3

Answer 10

Group 2
Pb2+, Bi3+, Cu2+

Group 3
Ni2+
 Fe2+
, Al3+
, Cr3+
)

Question 11

Ni 2+

Answer 11

Bright pink

Question 12

Al 3+

Answer 12

Red color

Question 13

Cr3+

Answer 13

Bright yelow orrange

Question 14

fe3+

Answer 14

Deep brown red color

Question 15

hinder anion analysis;

Answer 15

Ag+
, Hg2
2+
, Hg2+
, Pb2+
, Fe2+
, Fe3+
, Cu2+
, Ca2+
, Ba2+

Question 16

do not interfere with anion analysis

Answer 16

NH4+, K+ or Na+

Question 17

In order to remove interfering cations,

Answer 17

Boil the rest of SA left after cation analysis for ten minutes with Na2CO3

Question 18

Neutralize one part of the filtrate with HNO3 for detecting

Neutralize another part of the filtrate with HC1 for detecting

Answer 18

Cl-, SO42- ions

NO3- ion

Question 19

6M H2SO4

Answer 19

Gas evolution- carbonate

if not groups 2,3 and 4

Question 20

BaCl2

Answer 20

PO4-dissolved

, SO4- not dissolved