Tests for aqueous cations:

Question 1

Aluminum:

Answer 1

NaOH: white precipitate which dissolves in excess to produce a colorless solution
NH3: white precipitate which is insoluble in excess

Question 2

Ammonium:

Answer 2

NaOH: if warmed ammonia is produces which turns red litmus blue
NH3: -

Question 3

Calcium:

Answer 3

NaOH: white precipitate which is insoluble in excess
NH3: very faintly white precipitate

Question 4

Chromium (iii):

Answer 4

NaOH: green precipitate which dissolves in excess to produce a green solution
NH3: grey- green precipitate which is insoluble in excess

Question 5

Copper (ii):

Answer 5

NaOH: light blue precipitate which is insoluble in excess
NH3: light blue precipitate which is soluble in excess and dissolves to form a dark blue solution

Question 6

Iron (ii):

Answer 6

NaOH: green precipitate which is insoluble in excess
NH3: green precipitate which is insoluble in excess

Question 7

Iron (iii):

Answer 7

NaOH: red-brown precipitate which is insoluble in excess
NH3: red-brown precipitate which is insoluble in excess

Question 8

Zinc:

Answer 8

NaOH: white precipitate which dissolves in excess to produce a colorless solution
NH3: white precipitate which dissolves in excess to form a colorless solution