Test for ions

Question 1

Describe the rest for carbonate ions.

Answer 1

1) Add dilute nitric acid
2) CO2 gas forms (bubbles observed)
3) confirm it’s CO2 by bubbling the gas through the lime water. If CO2 is present it should turn the limewater cloudy.

Question 2

Describe the test for sulphate ions

Answer 2

1) Add barium chloride/barium nitrate solution

2) If you get a WHITE PRECIPITATE it’ll be barium sulfate, which tells you a sulphate is present

Question 3

What is the order of testing?

Answer 3

1) Carbonate Test
2) Sulphate Test
3) Halide Test

Question 4

Describe the test for positive ions

Answer 4

1) Add NaOH
2) Warm gently
3) Test has given with DAMP red litmus paper
4) If the litmus paper turns BLUE than ammonia gas is presnt

Question 5

Silver Nitrate solution is used to test for __________

Answer 5

Halides

Question 6

Describe the test for Halides

Answer 6

1) you add dilute nitric acid to remove ions that might interfere with the test
2) then you add silver nitrate solution
3) a precipitate is formed

• the colour of your precpitate identifes the halide
• then to be extra sure you can test you results by adding ammonia solution

Question 7

Sliver Nitrate test for halides
• Chlorine
• Bromine
• Iodine

Answer 7

Chlorine - WHITE precipitate - dissovles in DILUTE ammonia solution

Bromine - CREAM precipitate - dissolves in CONC. ammonia solution

Iodine - YELLOW precipitate - insoluble in CONC. ammonia solution

Question 8

why should you add dilute HCl to a solution before carrying out the barium chloride test?

Answer 8

The hydrochloric acid is added first to remove any carbonate ions that might be present - they would also produce a white precipitate, giving a false positive result.