Ion Test

Question 1

Test for Pb2+

Answer 1

Add NaOH
Gives a white precipitate

Question 2

Test for NH4+

Answer 2

Ammonia is produced when warming

Then test for ammonia by using damp red litmus paper in which ammonia will change the red to blue

Question 3

Test for Al3+

Answer 3

Add aqueous NaOH
creates white precipitate
precipitate dissolves in excess

Then, add aqueous ammonia
precipitate will not dissolve in excess

Question 4

Test for Zn2+

Answer 4

Add aqueous NaOH
creates white precipitate
precipitate dissolves in excess

Then, add aqueous ammonia
precipitate will dissolve in excess again

Question 5

Test for Ca2+

Answer 5

Add aqueous NaOH
creates white precipitate which will not dissolve in excess

Add aqueous ammonia
no precipitate made so nothing in excess

Question 6

Test for Cu2+

Answer 6

Add aqueous NaOH
creates blue precipitate which will not dissolve in excess

Add aqueous ammonia
creates gelatinous blue precipitate
Precipitate dissolves in excess to give deep blue clear solution

Question 7

Test for Fe2+

Answer 7

Add aqueous NaOH
creates green precipitate which will not dissolve in excess

Add aqueous ammonia
creates dirty green precipitate which will not dissolve in excess

Question 8

Test for Fe3+

Answer 8

Add aqueous NaOH
creates brown precipitate which does not dissolve in excess

Add aqueous ammonia
creates rust brown precipitate which will not dissolve in excess

Question 9

Test for Cr3+

Answer 9

Add aqueous NaOH
creates light green precipitate
precipitate dissolves in excess

Add aqueous ammonia
creates light green precipitate
precipitate dissolves to an extent in excess

Question 10

Test for CO3^2-

Answer 10

Add dilute acid
Result is effervescence and carbon dioxide is produced

Question 11

Test for Cl- (Chloride ion)

Answer 11

Acidify with dilute nitric acid, then add aqueous silver nitrate
Result is a white precipitate

Question 12

Test for Br- (Bromide ion)

Answer 12

Acidify with dilute nitric acid, then add aqueous silver nitrate
Result is a cream precipitate

Question 13

Test for I- (Iodide ion)

Answer 13

Acidify with dilute nitric acid, then add aqueous silver nitrate
Result is a yellow precipitate

Question 14

Test for NO3^- (Nitrate)

Answer 14

Add aqueous sodium hydroxide, then aluminium foil. After, warm carefully
Result is ammonia is produced

Question 15

Test for SO4^2- (Sulfate)

Answer 15

Acidify, then add aqueous barium nitrate or barium chloride
Result is white precipitate

Question 16

Test for SO3^2- (Sulfite)

Answer 16

Add dilute hydrochloric acid, warm gently and test for the presence of sulfur dioxide

Result will turn acidified potassium manganate from purple to colourless