rp4 Flashcards
testing for group 2 metals
1)4 testubes in rack
2)10 drops 0.1mol dm-3 barium chloride in first tube
3)10 drops dilute sodium hydroxide
4)swirl
5)keep adding until in excess
6)repeat for cal bromide,mag chloride,strontium chloride
positive test for mg2+ in ammonia
white precipitate
mg(oh)2
ca2+ positive solution in ammonium solution
no change seen
sr2+ ammonium solution pos
no change seen
ba 2+ ammonium solution positive
no change seen
mg2+ in excess sodium hydroxide
white precipitates
mgoh2
ca2+ in excess sodium hydroxide
white precipiate
caoh2
sr2+ in excess sodium hydroxide
slight white precipitate
ba 2+ in excess sodium hyroxide
no change seen
mg2+ in excess sulfuric acid
colourless
ca2+ in excess sulfuric acid
slight white precipitate
sr2+ in excess sulfuric acid
white precipitate
ba2+ in excess sulfuric acid
white precipitate
testing for sulfate ions
1)acidify whth dilute hcl and add few drops pf aq barium chloride
2)if sulfate present then a white preciipitate of brium sulfate is formed
testing for hydroxide ions
- 1cm3 of solution add to testube using pippette
-test the ph of the solution using red litmus paper
-presense of hydorxide ions will turn red litmus paper blue
test for carbonate ions
-1cm3 of dilute hcl dd to testube w pipette
-equal amount of sodium carbonate solution added to test tube
-bung with deliery tube added to test tube
-carbonate ions react with h ions fom acid to produce co2 gas
- co2 tuen limewater milky
testing ammonia ions
About 10 drops of a solution containing ammonium ions, such as ammonium chloride, should be added to a clean test tube
About 10 drops of sodium hydroxide should be added using a pipette
The test tube should be swirled carefully to ensure that it is mixed well
The test tube of the solution should then be placed in a beaker of water, and the beaker of water should be placed above a Bunsen burner, so that it can become a water bath
As the solution is heated gently, fumes will be produced
A pair of tongs should be used to hold a damp piece of red litmus paper near the mouth of the test tube, to test the fumes
The red litmus paper will change colour and become blue in the presence of ammonia gas
testing for halide ions
The sample being tested should be added using a pipette to a test tube
The test tube should be placed into a test tube rack
A small amount of nitric acid should be added to the sample using a pipette, followed by a small amount of silver nitrate solution
A precipitate will form, either white, cream or yellow, if a halide ion is present in the sample
The white precipitate will form if chloride ions are present in the sample
The white precipitate is AgCl
The cream precipitate will form if bromide ions are present in the sample
The cream precipitate is AgBr
The yellow precipitate will form if iodide ions are present in the sample
The yellow precipitate is AgI
