rp4

Question 1

testing for group 2 metals

Answer 1

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

Question 2

positive test for mg2+ in ammonia

Answer 2

white precipitate
mg(oh)2

Question 3

ca2+ positive solution in ammonium solution

Answer 3

no change seen

Question 4

sr2+ ammonium solution pos

Answer 4

no change seen

Question 5

ba 2+ ammonium solution positive

Answer 5

no change seen

Question 6

mg2+ in excess sodium hydroxide

Answer 6

white precipitates
mgoh2

Question 7

ca2+ in excess sodium hydroxide

Answer 7

white precipiate
caoh2

Question 8

sr2+ in excess sodium hydroxide

Answer 8

slight white precipitate

Question 9

ba 2+ in excess sodium hyroxide

Answer 9

no change seen

Question 10

mg2+ in excess sulfuric acid

Answer 10

colourless

Question 11

ca2+ in excess sulfuric acid

Answer 11

slight white precipitate

Question 12

sr2+ in excess sulfuric acid

Answer 12

white precipitate

Question 13

ba2+ in excess sulfuric acid

Answer 13

white precipitate

Question 14

testing for sulfate ions

Answer 14

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

Question 15

testing for hydroxide ions

Answer 15

• 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

Question 16

test for carbonate ions

Answer 16

-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

Question 17

testing ammonia ions

Answer 17

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

Question 18

testing for halide ions

Answer 18

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