C2.1 Qualitative Analysis

Question 1

What is meant by qualitative analysis?

Answer 1

Identifying if a substance is present

Question 2

How do you test for positive ion?

Answer 2

Add NaOH solution to the substance. A coloured precipitate should precipitate out of the solution as many metal hydroxides are insoluble.

Question 3

What are the positive results for cation tests with NaOH?

Answer 3

Calcium - White
Copper - Blue 
Iron (II) - Green
Iron (III) - Brown 
Aluminium - White, then dissolves again

Question 4

What is the positive test for ammonium when adding NaOH?

Answer 4

Heating gives off ammonia, which turns damp red litmus paper blue, and it smells putrid.

Question 5

What is the test for halide ions?

Answer 5

Add dilute nitric acid and the silver nitrate.

Question 6

What are the positive results for halide tests?

Answer 6

Chloride - White precipitate
Bromide - Cream precipitate
Iodide - Yellow precipitate

Question 7

What are the flame test results?

Answer 7

Potassium - Lilac
Sodium - Yellow
Copper - Blue/green
Calcium - Brick red

Question 8

How can a carbonate ion be identified?

Answer 8

By adding dilute HCl and bubbling any gas given off through limewater. If carbonate was present, the limewater will go cloudy.

Question 9

How do you test for sulphate ions?

Answer 9

Do the carbonate test and if you get no result, add barium sulphate.