Cations

Question 1

Groups:

Answer 1

1. dil HCl
2. H2S in dil HCl
   a. InSoluble in yellow ammonium sulphide
   b. Soluble in Yellow Ammonium Sulphide
3. NH4OH in NH4Cl
4. H2S in NH3 and NH4Cl
5. (NH4)2CO3 in NH4Cl and NH4OH
6. No common

Question 2

1. dil HCl

Answer 2

Pb2+ (PbCl2 -> Soluble in Hot water)
Hg+
Ag+

Question 3

2a. H2S in dil HCl
Insoluble in yellow ammonium sulphide

Answer 3

Hg2+
Cu2+
Cd2+
Bi3+
Pb2+

Ppt in both acidic and basic medium
lower ksp

Question 4

2b. H2S in dil HCl
Soluble in Yellow Ammonium Sulphide

Answer 4

As3+
As5+

Sb3+
Sb5+

Sn2+
Sn4+

ppt in both acidic/basic medium

Question 5

3. NH4OH in NH4Cl

Answer 5

Fe3+
Al3+
Cr3+

Question 6

4. H2S in NH3 and NH4Cl

Answer 6

Ni2+
Co2+
Mn2+
Zn2+

Only Basic Medium Ppt

Question 7

5. (NH4)2CO3 in NH4Cl and NH4OH

Answer 7

Ba2+
Sr2+
Ca2+

White Precipitate. Insoluble in water

Question 8

6. No common group re-agent

Answer 8

Mg2+
Na+
K+
NH4+ –> Na2HPO4

Question 9

0. NH4+

Answer 9

Liberates ammonia with NaOH, KOH

Not Mg(OH)2 -> Insoluble in water

Question 10

1. i) Pb2+ tests (Acid and Bases)

Answer 10

1. White ppt with dil. HCl -> Soluble in hot water and conc HCl
2. Insoluble Ph(OH2) with NH4OH
3. Soluble Pb(OH)2 with NaOH
   -> Oxidised to PbO2 with H2O2 and Na2S2O8

Question 11

1. i) Pb2+ Tests (Other re-agents)

Answer 11

1. K2CrO4
2. KI
3. KCN