Qualatative Analysis

Question 1

How do you test for halide ions

Answer 1

-dissolve in water and nitric acid
-add aqueous silver nitrate
-silver ions react with the halide ions forming a precipitate
-the precipitates are coloured
-add ammonia NH3 if you can’t tell the colour as halides has different solubilities in ammonia

Question 2

What are the observations for the halides and silver

Answer 2

Chloride - white
Bromine - cream
Iodine - yellow

Question 3

Why do we use nitric acid

Answer 3

To get rid of false positives
(Silver carbonate has a white p and is a false positive)
Nitric acids gets rid of carbonates and turns them into carbon dioxide
Co3 + 2h - co2 + h20

Question 4

Why can’t hydrochloride acid or sulphuric acid be used

Answer 4

Because silver sulphate and silver. Chloride are white precipitates

Question 5

How do you test for carbonates

Answer 5

Add nitric acid and it turns to co2 - fizzing
Co3 + h - co2 + h20

Question 6

How do you test for sulphates

Answer 6

Add barium nitrate
Turns into a solid white precipitate
So4 + ba - baso4

Question 7

How do you test for ammonium

Answer 7

Heat with NaOH
Turns red litmus paper blue
NH4 + OH - NH3 + H20

Question 8

What order should tests be completed in

Answer 8

Carbonates - sulfates - halides

Question 9

What are the halides solubilities in ammonia

Answer 9

Chloride - soluble in dilute ammonia
Bromide - soluble in concentrated ammonia
Iodide - insoluble in concentrated ammonia