3.1.4 Qualitative Analysis

Question 1

What are anions also known as?

Answer 1

Negative ipns

Question 2

How can you test for carbonate ions, CO3 2- ?

Answer 2

Add strong acid to the sample
Collect the gas produced
Pass through line water

Question 3

What are observations for a positive test of carbonate ions, CO3 2-?

Answer 3

Fizzing
Lime water turns cloudy

Question 4

How can you test for sulphate ions, SO4 2-?

Answer 4

Add dilute hydrochloride acid and barium chloride to the sample Collect

Question 5

What are the observations for a positive test of sulfate ions, SO4 2-?

Answer 5

White precipitation of barium sulfate is produced

Question 6

What is the test for hairline ions?

Answer 6

Acidified AgNO3

Question 7

Why do you add HNO3 to the test for hairline ions and not HCl?

Answer 7

To remove CO3 2-
Adding HCl would add Cl- ions, giving a false positive result

Question 8

When testing for carbonate, sulfate and hairline ions, in which order should the tests be carried out and why?

Answer 8

Carbonate test
Sulfate test
Halide test

Because barium ions forms insolvable precipitate of BaCO3 and silver ions form insoluble precipitate of Ag2SO4

Question 9

What are cations also known as?

Answer 9

Positive ions

Question 10

How can you test for ammonium ions, NH4 +?

Answer 10

Add sodium hydroxide to sample and warm it
Test gas produced with red litmas paper