Sodium hydroxide test

Question 1

Magnesium sulfate (MgSO₄)

Answer 1

White precipitate (doesn’t dissolve in excess NaOH)

Question 2

Calcium chloride (CaCl₂)

Answer 2

White precipitate (doesn’t dissolve in excess NaOH)

Question 3

Aluminium sulfate [Al₂(SO₄)₃]

Answer 3

White precipitate (does dissolve in excess NaOH)

Question 4

Iron (II) sulfate (FeSO₄)

Answer 4

Green precipitate

Question 5

Iron (III) chloride (FeCl₃)

Answer 5

Brown precipitate

Question 6

Copper (II) sulfate (CuSO₄)

Answer 6

Blue precipitate

Question 7

Method

Answer 7

1. Put 2cm³ of the test solution in test tube.
2. Add sodium hydroxide drop-wise until no further colour change.
3. Note the colour of each precipitate and if it dissolves or not.