Chemical analysis

Question 1

Colour of flame produced by lithium

Answer 1

Crimson

Question 2

Colour of flame produced by sodium

Answer 2

Yellow

Question 3

Colour of flame produced by potassium

Answer 3

Lilac

Question 4

Colour of flame produced by calcium

Answer 4

Orange-red

Question 5

Colour of flame produced by copper

Answer 5

Green

Question 6

Test for carbonates

Answer 6

Add dilute hydrochloric acid, bubble products produced through limewater.
If it turns cloudy (CO2 is present) the test is positive for carbonates.

Question 7

Test of sulfates

Answer 7

Add dilute hydrochloric acid (removes other ions which are impurities), add barium chloride solution.
If a white precipitate forms (BaSO4) the test is positive for sulfates.

Question 8

Test for halides

Answer 8

Add dilute nitric acid. Add silver nitrate solution, halides react with silver to form precipitates. Chlorine- white, bromine- cream, iodine- yellow.

Question 9

What is the colour of the precipitate copper (II) hydroxide?

Answer 9

Blue

Question 10

What is the colour of the precipitate iron (II) hydroxide?

Answer 10

Green

Question 11

What is the colour of the precipitate iron (III) hydroxide?

Answer 11

Brown

Question 12

What is the colour of the precipitates calcium hydroxide, magnesium hydroxide and aluminium hydroxide?

Answer 12

White

Question 13

Which is the only precipitate to dissolve in excess sodium hydroxide?

Answer 13

Aluminium hydroxide. It forms a white precipitate but redissolves in excess NaOH to form a colourless solution.

Question 14

What are the three main advantages of instrumental methods?

Answer 14

They are very accurate, very sensitive and rapid.