Test For Ions/Atoms

Question 1

Lithium in the flame test.

Answer 1

Crimson

Question 2

Sodium.

Answer 2

Yellow/orange.

Question 3

Potassium

Answer 3

Lilac (pink through cobalt glass)

Question 4

Calcium

Answer 4

Brick red

Question 5

Barium

Answer 5

Apple green

Question 6

Copper

Answer 6

Green-blue

Question 7

What is the test for ammonium?

Answer 7

Warm with a solution of sodium hydroxide. A pungent smell will be observed.
This is due to the ammonium reacting with the OH ions, water and ammonia is formed.

Question 8

What is the test for sulphate ions?

Answer 8

Make a solution and add a solution of barium chloride or barium nitrate, a white precipitate will be formed.

Question 9

How do you perform the test for halide ions?

Answer 9

Make a solution in dilute nitric acid and add silver nitrate solution.

Question 10

Chloride.

Answer 10

White precipitate, soluble in dilute ammonia solution.

Question 11

Bromide

Answer 11

Cream precipitate, soluble in concentrated ammonia solution.

Question 12

Iodide.

Answer 12

Yellow precipitate, insoluble in concentrated concentrated ammonia solution.

Question 13

What is the test for carbonate ions?

Answer 13

Add dilute acid to form colourless gas which turns limewater milky.

Question 14

What is the test for iodine?

Answer 14

Add a few drops of starch solution, the solution will turn blue-black.

Question 15

Hydrogen.

Answer 15

Gives a pop with a burning splint.

Question 16

Oxygen

Answer 16

Relight a glowing splint.

Question 17

Chlorine

Answer 17

Bleaches damp litmus/Universal indicator.

Question 18

Carbon dioxide.

Answer 18

Bubble through limewater, limewater turns milky.

Question 19

Hydrochloric acid.

Answer 19

White fumes produced when a glass rod is dipped in concentrated ammonia.

Question 20

Ammonia.

Answer 20

White fumes produced when glass rod is dipped in concentrated hydrochloric acid

Question 21

What molecule is present if there is a colourless liquid with alcohol smell?

Answer 21

Possibly an alcohol

Question 22

What is produced when a colourless liquid with a sharp irritating smell is produced?

Answer 22

Possibly a carboxylic acid

Question 23

How do you test for carbon content?

Answer 23

Place a few drops of the liquid on a watch glass and light with a splint.

Question 24

What is produced in a low carbon content (alcohol)?

Answer 24

Non sooty/clean blue flame.

Question 25

What is produced in a high carbon content?

Answer 25

Sooty yellow/orange flame.

Question 26

How do you test for an alcohol group?

Answer 26

Phosphorus pentachloride.

Question 27

How do you carry out the test to determine the alcohol group?

Answer 27

Add a few crystals of PCl5 to a few cm3 of the liquid. Test any gas released with a glass rod dipped in concentrated ammonia solution.

Question 28

What is produced if an alcohol is present?

Answer 28

Misty fumes, solid disappears, white smoke (ammonium chloride).

Question 29

What is observed if an alcohol isn't present?

Answer 29

No gas released, no white smoke with conc. ammonia solution.

Question 30

How do you test for a primary/secondary alcohol as opposed to a tertiary?

Answer 30

Mix a few cm3 of the liquid or solution with acidified potassium dichromate solution in a test tube and warm in a water bath.

Question 31

What is observed if a primary alcohol is present?

Answer 31

Orange solution changes to green, change in smell.

Question 32

What is observed if a primary alcohol is not present?

Answer 32

Solution remains orange.