Cations

Question 1

Ammonium (NH4+)

Answer 1

Add dilute sodium hydroxide, and then heat gently. Damp red litmus paper turns blue and ammonia gas is released.

Question 2

Copper (II)

Answer 2

Add dilute sodium hydroxide OR ammonia solution. Pale blue precipitate forms. However, as you add more ammonia, the solution dissolves, leading to a deep blue solution.

Question 3

Iron (II)

Answer 3

Add dilute sodium hydroxide OR ammonia solution. Pale green precipitation forms.

Question 4

Iron (III)

Answer 4

Add dilute sodium hydroxide OR ammonia solution. Red-brown precipitate forms.

Question 5

Zinc

Answer 5

Add dilute sodium hydroxide OR ammonia solution. White precipitate forms.