Tests for Ions- A-Level Chemistry Questions & Answers

How do you test for sulphates? Add dilute HCl and barium chloride solution How do you know if the test result is positive for sulphates? White precipitate formed of barium sulphate How do you test for halides? Add nitric acid and then silver nitrate Which halide dissolves in dilute and conc NH3? Chloride Which halide is not soluble in dilute NH3, but in conc NH3? Bromide How do you know if the test result is positive for halides? Precipitate forms- White (chloride), cream (bromide), yellow (iodide) What do you use to test for ammonium compounds? Damp red litmus and sodium hydroxide for ammonium solutions How do you know if the test result is positive for ammonium compounds? Damp red litmus goes blue , after heating compound to gaseous form What is the order for the ion tests? Carbonates, Sulphates and halides What do you use to test for an aldehyde? Tollens What do you use to test for a carbonyl group? 2,4 DNP What do you use to test for a carboxylic acid? PCl5 or litmus or NaCO3 What do you use to test for phenol? NaOH and then carbonate or FeCL3 What do you use to test for ammonium ion? cold NaOH What do you use to test for an amine? Add universal indicator, and a blue or purple solution should form How do you test for a carboxylic acid? Add Na2CO3 which will produce CO2. Then add limewater and a cloudy solution should be present How do you test for an acyl chloride? Add water. White steamy fumes will be given off If you were blind, how would you test for an alcohol? Add COOH and H2SO4 catalyst- this produces an ester which will have a fruity smell How do you test for haloalkanes? Add NaOH and then add (Ag(NO3)2)2+ and HNO3 acid to confirm precipitate