8.3 Qualitative Analysis

Question 1

Describe the carbonate ion test.

Answer 1

Add dilute nitric acid to solid/solution being tested.
If there are bubbles the compound could be a carbonate.
Bubble the gas through limewater.
If limewater turns cloudy CO2 is present.

Question 2

Describe the sulfate test.

Answer 2

Add barium ions to unknown solution if sulfate ions are present a white precipitate of barium sulfate forms.

Question 3

Describe the halide test.

Answer 3

Add a few drops of nitric acid.
Add a few drops of silver nitrate solution.
Observe colour change

Question 4

What is the result of the Cl- ion?

Answer 4

White precipitate

Question 5

What is the result of the Br- ion?

Answer 5

Cream precipitate

Question 6

What is the result of the I- ion?

Answer 6

Yellow precipitate

Question 7

How can you differ the result of Br- and I- ion?

Answer 7

Br- ion is soluble in concentrated aqueous ammonia whereas I- ion is insoluble.

Question 8

Describe the test for an ammonium ion.

Answer 8

Add aqueous sodium hydroxide to unknown.
Warm the mixture.
Test any gas involved with damp litmus paper.
If litmus paper turns blue the unknown is an ammonium salt.