4: identifying anions and cations

Question 1

Observation of ammonium chloride solution and NaOH?

Answer 1

• white precipitate
• red litmus turns purple/blue (alkaline gas)

Question 2

Observation of Ca2+ and NaOH?

Answer 2

White precipitate

Question 3

Observation of Ba2+ and NaOH?

Answer 3

White precipitate

Question 4

Observation of Ca2+ and sulfuric acid?

Answer 4

No change

Question 5

Observation of Ba2+ and sulfuric acid?

Answer 5

White precipitate

Question 6

Calcium flame colour:

Answer 6

Orange

Question 7

Strontium flame colour:

Answer 7

Crimson

Question 8

Barium flame colour

Answer 8

Pale green

Question 9

Hydroxide ions test:

Answer 9

• add universal indicator
• turns dark blue

Question 10

Sodium carbonate solution + HCl:

Answer 10

• Observation : effervescence
• test the gas given off with limewater: turns chalky, white precipitate

Question 11

Colours of halide precipitates:

Answer 11

Chloride - white
Bromide - cream
Iodide - yellow

Question 12

Silver halides solubilities in dilute ammonia:

Answer 12

AgCl - soluble
AgBr - insoluble
AgI - insoluble

Question 13

Silver halides solubilities in concentrated ammonia:

Answer 13

AgCl - soluble
AgBr - soluble
AgI - insoluble

Question 14

Why can’t HCl be added to remove sulphites and carbonates?

Answer 14

It contains Cl- ions so will give a precipitate

Question 15

Observation when HCl and barium chloride solution are added to magnesium sulfate solution:

Answer 15

White precipitate (BaSO4)