Required practical 4 Tests for cations and anions

. Add 10 drops of your 0.1mol/dm group 2 metal halide solution . Add 10 drops of 0.6mol/dm sodium hydroxide solution, mix, then add it until it’s in excess . Gently shake the solution

. Initially colourless solution . After 10 drops it is still colourless . In excess, it’s still colourless

. Initially colourless . After 10 drops a slight white precipitate forms . In excess, there is still a slight white precipitate The slight white precipitate is calcium hydroxide

. Initially colourless . After 10 drops a slight white precipitate forms . In excess, white precipitate forms

. Barium chloride: solution stays colourless Going down the group, they react less with it. So Magnesium chloride forms white precipitate but barium chloride stays colourless with it

. Add 10 drops of 0.1mol/dm barium chloride to a test tube . Add 10 drops of 1.0mol/dm sulfuric acid. and mix . Then add it in excess and gently shake Repeat test with calcium bromide, magnesium chloride and strontium chloride At the top of the group it forms a slight precipitate and goes colourless, down the group there is more of a white precipitate

. It’s initially colourless before H2SO4 is added And it forms a white precipitate after it is added, and also when it is in excess You may add HCl also, to remove any carbonate ions which can form calcium carbonate with calcium when they react together

. Initially it is colourless . After 10 drops a white precipitate forms . In excess, It stays a white precipitate

. It is initially colourless . A slight white precipitate forms after 10 drops . And a slight white precipitate forms in excess acid

. It is initially colourless . A slight white precipitate forms after 10 drops . It goes colourless again in excess

. Add 10 drops of 0.1mol/dm of ammonium chloride to a test tube . Add 10 drops of 0.6moldm sodium hydroxide solution to it . Warm solution in water bath because ammonia gas is very soluble . Hold damp red litmus paper over the test tube with forceps as fumes are released . The fumes should turn it blue

. Add an equal volume of dilute HCl to sodium carbonate solution in a test tube . Use a test tube to bubble it through calcium hydroxide (limewater) which will form calcium carbonate . Put a stopper into the test tube containing limewater and shake Positive test turns it from colourless to cloudy

Na2C03 + 2HCl —> 2NaCl + H20 + CO2 CO2 + Ca(OH)2 —> CaCO3 + H20

. Add an equal volume of dilute HCl and Barium chloride to the solution containing sulfate ions . If there are sulfate ions present, barium sulfate forms which is a white precipitate

MgSO4 + BaCl2 —> BaSO4(s) + MgCl2(aq)

You have potassium chloride, bromide and iodide . Add 10 drops of potassium chloride to a test tube and add 5 drops nitric acid . Then add 10 drops silver nitrate to the solution . Swirl the test tube so the precipitate can evenly distribute

Chloride ions: White precipitate Bromide ions: Cream precipitate Iodide ions: Yellow precipitate

. With concentrated and dilute ammonia solution, chloride ions dissolve AgCl(s) + 2NH3 —> [Ag(NH3)2]+ + Cl- . With concentrated ammonia solution, bromide ions dissolve AgBr(s) + 2NH3(aq) → Ag [(NH3)2]+(aq) + Br- . Iodide ions don’t dissolve in either so stays a yellow precipitate No reaction

.Place a small spatula of solid potassium chloride in a dry test tube in a test tube rack . Working in a fume cupboard, add a few drops of concentrated sulfuric acid . Record observations . Test gas evolved with blue litmus paper . Repeat experiment with potassium bromide and potassium iodide

. White steamy fumes . Blue litmus paper turns red

. Orange fumes . It turns blue litmus paper red

. Purple fumes and a purple/black solid . Blue litmus paper turns red

Flouride ion