Qualitative Analysis

Question 1

In what order should tests for ions be performed in when there is a mixture of ions present?

Answer 1

Carbonate, sulfate, then halide.

Question 2

How do i test for carbonate ions?

Answer 2

Add and acid such as HCL
It will fizz and CO2 gas is given off
Gas can be collected through lime water which will turn cloudy, confirming its identity as CO2

Question 3

How do i test for sulfate ions?

Answer 3

Add acidified BaCl2
Reacts to form white precipitate of barium sulfate

Question 4

How do i test for halide ions?

Answer 4

Using acidified AgNO3, halide ions react to form different coloured precipitates depending on the ion present. the halide can be further tested with dilute/conc ammonia.

Check PMT for table.

Question 5

How do I test for ammonium ions?

Answer 5

Adding NaOH
Gently warming results in formation of ammonium gas, which is basic
Presence of ammonium ions can be tested by holding damp red litmus paper over the ammonia gas
Turns blue