Chemistry Tests

Test for Cl^- ions in solution  

Add nitric acid then silver nitrate this produces a white precipitate the dissolves in dilute ammonia. 

Test for Br^- ions in solution 

Add nitric acid then silver nitrate this produces a cream precipitate that only dissolves in conc ammonia. 

Test for I^- ions in solution 

Add nitric acid then silver nitrate this produces a yellow precipitate which is insoluble in conc ammonia. 

Test for Cl^- ions in solids  

Add conc sulphuric acid, white steamy fumes are produced that turns blue litmus paper red. 

Test for Br^- ions in solids 

Add conc sulphuric acid, orange/brown fumes are produced. Potassium dichromate absorbed on filter paper goes from yellow to green when the fumes pass over it. 

Test for I^- ions in solids 

Add conc sulphuric acid, purple fumes are produced. Lead nitrate solution absorbed on filter paper goes from colourless to yellow when the fumes pass over it. 

Test for CO₃^2- 

Add acid, collect gas formed and pass through limewater. If carbonate ions were present the limewater goes cloudy. 

Test for SO₄^2- 

Add hydrochloric acid then barium chloride this produces a white precipitate. 

Test for unsaturation (eg a double bond)  

Add Bromine water - Observation is orange to colourless 

Test for an organic carboxylic acid 

Add NaHCO3 - Observation is effervescence  

Test for a primary or secondary alcohol 

Add sulphuric acid then sodium dichromate (VI) 

Observation is orange to green solution  

Test for aldehydes 

Add Fehlings solution and place in a hot water bath (70 degrees) for 5-10 mins 

Observation is blue solution to a brick red precipitate 

OR 

Add Tollens reagent  and place in a hot water bath (70 degrees) for 5-10 mins 

Observation is colourless solution to a silver mirror 

Test for haloalkanes 

Add NaOH and warm in a water bath 

Then add HNO3 followed by AgNO3 

Observation is colourless to a white precipitate if a chloro 

 (cream if bromo/yellow if iodo)