tests for cations

Question 1

Copper(II) Cu2+ Reaction with NaOH (aq)

strong alkaline

Answer 1

• -> Forming blue precipitate of Cu(OH)2

- -> The precipitate is insoluble in excess NaOH

Question 2

Copper(II) Cu2+ Reaction with NH3(aq)(weak alkaline)

Answer 2

–> Forming blue precipitate of Cu(OH)2
–> Precipitate dissolves in excess NH3 to give dark blue
complex ion

Question 3

Iron(II) Fe2+ Reaction with NaOH (aq)(strong alkaline)

Answer 3

• -> Forming green precipitate of Fe(OH)2

- -> The precipitate is insoluble in excess NaOH

Question 4

Iron(II) Fe2+ Reaction with NH3 (aq) (weak alkaline)

Answer 4

• -> Forming green precipitate of Fe(OH)2

- -> Precipitate is insoluble in excess NH3

Question 5

Iron(III) Fe3+ Reaction with NaOH (aq)(strong alkaline)

Answer 5

• -> Forming reddish-brown precipitate of Fe(OH)3

- -> Precipitate is insoluble in excess NaOH

Question 6

Iron(III) Fe3+ Reaction with NH3 (aq) (weak alkaline)

Answer 6

• -> Forming reddish-brown precipitate of Fe(OH)3

- -> Precipitate is insoluble in excess NH3

Question 7

Calcium Ca2+ Reaction with NaOH (aq)(strong alkaline)

Answer 7

• -> Forming white precipitate of Ca(OH)2

- -> Precipitate is insoluble in excess NaOH

Question 8

Calcium Ca2+ Reaction with NH3 (aq) (weak alkaline)

Answer 8

No observable reaction

Question 9

Aluminium Al3+ Reaction with NaOH (aq)(strong alkaline)

Answer 9

• -> Forming white precipitate of Al(OH)3

- -> Precipitate dissolves in excess NaOH to give a colorless solution

Question 10

Aluminium Al3+ Reaction with NH3 (aq) (weak alkaline)

Answer 10

• -> Forming white precipitate of Al(OH)3

- -> Precipitate is insoluble in excess NH3

Question 11

Lead(II) Pb2+Reaction with NaOH (aq)(strong alkaline)

Answer 11

• -> Forming white precipitate of Pb(OH)2

- -> Precipitate dissolves in excess NaOH to give a colorless solution

Question 12

Lead(II) Pb2+ Reaction with NH3 (aq) (weak alkaline)

Answer 12

• -> Forming white precipitate of Pb(OH)2

- -> The precipitate is insoluble in excess NH3

Question 13

Zinc Zn2+ Reaction with NaOH (aq)(strong alkaline)

Answer 13

• -> Forming white precipitate of Zn(OH)2

- -> Precipitate dissolves in excess NaOH to give a colorless solution

Question 14

Zinc Zn2+ Reaction with NH3 (aq)(weak alkaline)

Answer 14

• -> Forming white precipitate of Zn(OH)2

- -> Precipitate dissolves in excess NH3 to give a colorless solution

Question 15

Ammonium NH4+ Reaction with NaOH (aq)(strong alkaline)

Answer 15

• -> No precipitate formed

- -> Warming the solution produces pungent ammonia gas which turns moist red litmus blue

Question 16

Ammonium NH4+ Reaction with NH3 (aq)(weak alkaline)

Answer 16

–> No observable reaction