Qualitative anaylsis

Question 1

salts containing Na+,K+Ca2+,Mg2+,Al3+,Zn2+,NH4+

Answer 1

Solid: White
Aqueous salt solution: colourless

Question 2

CuSO4, Cu(NO3)2

Answer 2

Solid: Blue (hydrated salts)
Aqueous salt solution: Blue

Question 3

CuCl2

Answer 3

Solid: Green
Aqueous salt solution: Blue

Question 4

CuCO3

Answer 4

Solid: Green
Aqueous salt solution: insoluble

Question 5

FeSO4, Fe(NO3)2,FeCl2

Answer 5

Solid: Green
Aqueous salt solution: Green

Question 6

Fe(SO4)3, Fe(NO3)3,FeCl3

Answer 6

Solid: Brown
Aqueous salt solution: Yellow

Question 7

PbO

Answer 7

Solid: Brown when hot, yellow when cold
Aqueous salt solution: insoluble

Question 8

CuO

Answer 8

Solid: Black
Aqueous salt solution: insoluble

Question 9

ZnO

Answer 9

Solid: Yellow when hot, white when cold
Aqueous salt solution: insoluble

Question 10

PbCl2

Answer 10

Solid: White
Aqueous salt solution: insoluble in cold water, soluble in hot water to give a colourless solution

Question 11

PbI2

Answer 11

Solid: Yellow
Aqueous salt solution: insoluble in cold water, soluble in hot water to give a colourless solution

Question 12

Ca2+, add NaOH

Answer 12

white ppt, insoluble in excess

Question 13

Zn2+, add NaOH

Answer 13

white ppt, soluble in excess

Question 14

Al3+, add NaOH

Answer 14

white ppt, soluble in excess

Question 15

Pb2+, add NaOH

Answer 15

white ppt, soluble in excess

Question 16

Fe2+, add NaOH

Answer 16

green ppt, insoluble in excess

Question 17

Fe3+, add NaOH

Answer 17

reddish brown ppt, insoluble in excess

Question 18

Cu2+, add NaOH

Answer 18

blue ppt, insoluble in excess

Question 19

NH4+, add NaOH

Answer 19

no ppt, NH3 evolved

Question 20

Ca2+, add NH3

Answer 20

no ppt

Question 21

Zn2+, add NH3

Answer 21

white ppt, soluble in excess (same)

Question 22

Al3+, add NH3

Answer 22

white ppt, insoluble in excess

Question 23

Pb2+, add NH3

Answer 23

white ppt, insoluble in excess

Question 24

Fe2+, add NH3

Answer 24

green ppt, insoluble in excess (same)

Question 25

Fe3+, add NH3

Answer 25

reddish brown ppt, insoluble in excess (same)

Question 26

Cu2+, add NH3

Answer 26

blue ppt, soluble in excess to give a dark blue solution

Question 27

NH4+

Answer 27

no ppt

Question 28

Add dilute H2SO4

Answer 28

white ppt, cations are Ba2+ and Pb2+

Question 29

Dilute HCl

Answer 29

White ppt, cation is Pb2+, ppt will be soluble as solubility increases on heating. Heating causes the solution to be saturated and white crystals will appear

Question 30

Aqueous KI

Answer 30

yellow ppt, cation is Pb2+.Heating causes the solution to be saturated and white crystals will appear

white ppt in brown solution, cation is Cu2+. Redox reaction occurs and Cu2+ is reduced to Cu+, and I- is oxidised to I2. White ppt is hence Cu2I2, while brown solution is aq I2.

brown solution, cation is one of the oxidising agents are present. redox reaction occurs where Fe3+ is reduced to Fe2+, I- is oxidised to I2.

Question 31

Acidified KMnO4/ K2Cr2O7

Answer 31

KMnO4 turn from purple to colourless when reducing agents are present. K2Cr2O7 turns from orange to green.

Examples of reducing agents: Fe2+, Cu+, Zn2+)

Question 32

Oxidising agents

Answer 32

Ag+, Fe3+, Cu2+, Pb4+

Question 33

CO3 2-

Answer 33

add dilute NHO3 to 1 cm3. Effervescence of colourless and odourless gas, forms white ppt with limewater

Question 34

Cl-

Answer 34

add dilute HNO3, followed by aqueous silver nitrate, white ppt of AgCl is formed

Question 35

I-

Answer 35

add dilute HNO3 followed by aqueous silver nitrate. Yellow ppt of Agl is formed

Question 36

SO4 2-

Answer 36

add dilute HNO3. followed by aqueous barium nitrate or aqueous barium chloride. White ppt of BaSO4 is formed

Question 37

NO3-

Answer 37

add NaOH, followed by aluminum powder/foil. Warm, test the gas evolved with damp red litmus paper. Colourless and pungent gas is evolved which turn damp red litmus paper blue. Gas evolved is NH3