Ions Testing Memory

Question 1

Test for a carbonate anion (CO3)^2-
And positive result

Answer 1

Add dilute nitric acid HNO3

Results in fizzing (CO2 bubbles)

Question 2

Test for sulphate anion (SO4)^2-
and positive result

Answer 2

Add aqueous Ba(NO3)2 or aqueous Ba ions

results in a white precipitate of (BaSO4)

Question 3

Test for Halide anion (X)^-
and positive result

Answer 3

Add Silver chloride (AgNO3)

results in white/cream/yellow precipitate (AgX)
use ammonia to differentiate based on solubility

Question 4

test for Chloride anion (Cl)^-
and positive result

Answer 4

add aqueous silver Nitrate (AgNO3)
results in a white precipitate (AgCl)

add dilute aqueous ammonia (NH3)
precipitate will dissolve

Question 5

test for Bromide anion (Br)^-
and positive result

Answer 5

add aqueous silver Nitrate (AgNO3)
results in a cream precipitate (AgCl)

Add concentrated aqueous ammonia (NH3)
precipitate will dissolve

Question 6

test for iodide anion (I)^-
and positive result

Answer 6

add aqueous silver Nitrate (AgNO3)
results in a yellow precipitate (AgCl)

Add concentrated aqueous ammonia (NH3)
precipitate will not dissolve

Question 7

What order should you test for Anions and why

Answer 7

Carbonate -> sulphate -> Halide

as carbonate and sulphate will BOTH give a positive result for a SULPHATE test.
Sulphates will also give a False positive result for a Halide test.

Question 8

How to tell difference between halide test results

Answer 8

Add dilute aqueous ammonia, Silver chloride will dissolve.

Add conc aqueous ammonia, Silver Bromide will dissolve

Silver iodide will not dissolve