Tests For Anions And Cations

Question 1

Test for carbonates

Answer 1

Carbonate + acid = CO2
Add dilute nitric acid and if there’s bubbles, bubble through limewater
This goes cloudy in the presence of CO2

Question 2

Test for sulphate

Answer 2

BaSO4 forms white precipitate so add Barium2+ (aq) ions to test for a sulphate (barium nitrate)

Question 3

Halide tests (process)

Answer 3

Silver halides are insoluble so add nitric acid then silver nitrate
Ag+ + X- -> AgX (s)

Question 4

Halide test chloride ppt

Answer 4

White

Soluble in dilute NH3

Question 5

Bromide halide test ppt

Answer 5

Cream

Soluble in conc NH3

Question 6

Iodide halide test ppt

Answer 6

Yellow

Insoluble

Question 7

Order of anion tests

Answer 7

Carbonate, Sulfate, halide

Question 8

Test for ammonium ion

Answer 8

Warm gently with dilute NaOH
NH4+ + OH- -> NH3(g) + H2O
Presence of ammonia turns damp red litmus paper blue