AQA A-level chemistry chemical Tests Questions and Answers

AQA A-level chemistry chemical tests


test for Carbon Dioxide (CO2 ) - Answer-turns limewater milky (sparingly soluble Ca(OH) 2 forms
insoluble CaCO3 )



Chlorine (Cl2 ) test - Answer-bleaches damp litmus paper (Cl2 reacts with water to form HCl and HOCl)



Hydrogen (H2 ) test - Answer-pops with a lighted splint



Oxygen (O2 ) test - Answer-relights a glowing splint



Carbonate (CO 3 2- ) test - Answer-add dilute acid; effervescence, carbon dioxide produced



Sulfate (SO4 2- ) test - Answer-add dilute nitric acid then aqueous barium nitrate. Gives white precipitate



Chloride (Cl - ) test - Answer-add dilute nitric acid then aqueous silver nitrate. Gives white precipitate.
Dissolves in dilute ammonia to give colourless solution (of [Ag(NH 3 ) 2 ] + )



Bromide (Br - ) test - Answer-add dilute nitric acid then aqueous silver nitrate. Gives cream precipitate.
Dissolves in concentrated ammonia but not in dilute ammonia



Iodide (I - ) test - Answer-add dilute nitric acid then aqueous silver nitrate. Gives yellow precipitate. Does
not dissolve in either concentrated or dilute ammonia



Iron II (Fe 2+ ) test - Answer-add aqueous sodium hydroxide gives green precipitate, insoluble in excess