Tests for aqueous cations (+)

Question 1

Aluminium (Al^3+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 1

1-White PPT, soluble in excess giving a colourless solution

2-White PPT, insoluble in excess

Question 2

Ammonium (NH4+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 2

1-Ammonia is produced on warming

2-No change

Question 3

Calcium (Ca^2+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 3

1-White PPT, insoluble in excess

2-No PPT, or a very slight white PPT

Question 4

Copper(II) (Cu^2+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 4

1-Light blue PPT, insoluble in excess

2-Light blue PPT, soluble in excess giving a dark blue solution

Question 5

Iron(II) (Fe^2+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 5

1-Green PPT, insoluble in excess

2-Green PPT, insoluble in excess

Question 6

Iron(III) (Fe^3+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 6

1-Red-brown PPT, insoluble in excess

2-Red-brown PPT, insoluble in excess

Question 7

Zinc (Zn^2+)

Adding:
1-Aqueous sodium hydroxide
2-Aqueous ammonia

Answer 7

1-White PPT, soluble in excess giving a colourless solution

2-White PPT, soluble in excess giving a colourless solution