Chemical Diagnostic Tests

Question 1

Test for hydrogen

Answer 1

Squeaky pop sound with a lighted splint

Question 2

Test for oxygen

Answer 2

Relights a glowing splint

Question 3

Tests for water

Answer 3

White anhydrous copper sulphate turns blue

Cobalt chloride paper turns from blue to pink

Question 4

What are the results for the flame test and what does it test for

Answer 4

Positive ions
Crimson: lithium
Golden yellow: sodium
Lilac: potassium
Orange - red: calcium
Green: copper

Question 5

What are the precipitate colours and process for positive ions

Answer 5

Dissolve ionic compound in deionised water and add sodium hydroxide
Blue precipitate: copper (II)
Green precipitate: iron (II)
Brown precipitate: iron (III)
White precipitate then colourless: aluminium ions
White precipitate: magnesium ions, calcium

Question 6

What is the test for a carbonate ion

Answer 6

Hydrochloric acid mixed with the ionic compound with a tube connected to limewater.
If the solution fizzes and makes the lime water milky then it is a carbonate

Question 7

Test for a halide ion

Answer 7

Dissolve ionic compound in water and add nitric acid then silver nitrate
Yellow precipitate: iodide ions
Cream precipitate: bromide ions
White precipitate: chloride ions

Question 8

Sulfate ion test

Answer 8

Dissolve ionic compound in water then add hydrochloric acid then barium chloride
White precipitate forms