C4.2

Question 1

Flame test colour of lithium

Answer 1

Red/crimson

Question 2

Flame test colour of sodium

Answer 2

Yellow

Question 3

Flame test colour for potassium

Answer 3

Lilac

Question 4

Flame test colour for calcium

Answer 4

Orange red

Question 5

Flame test colour for copper

Answer 5

Green blue

Question 6

Precipitate colour for iron(II) and sodium hydroxide

Answer 6

Green, then slowly turns brown

Question 7

Precipitate colour for iron (III) and sodium hydroxide

Answer 7

Orange-brown

Question 8

Precipitate colour for copper (II)

Answer 8

Blue

Question 9

Precipitate colour for calcium and sodium hydroxide

Answer 9

White (insoluble in excess sodium hydroxide)

Question 10

Precipitate colour for zinc and sodium hydroxide

Answer 10

White (dissolves in excess sodium hydroxide)

Question 11

How to test for carbonate

Answer 11

• Add a metal carbonate to a dilute acid.
• If it bubbles, test the gas for CO2 (using the lime water test).
• If limewater turns cloudy CO2 has been produced.
• Therefore it is a carbonate.

Question 12

How to test for sulphate

Answer 12

• Add dilute HCl acid to remove any carbonate ions.
  (Can’t use sulphuric acid to remove carbonate as it has sulphate ions which then gives the test a false positive)
• Then add barium chloride solution.
• If a white precipitate forms sulphate ions are present.

Question 13

Testing for halides

Answer 13

• Add dilute nitric acid to dissolve the substance and remove any carbonate ions.
• Then add silver nitrate
• If a precipitate forms, a halide ion is present.
• Chloride = white precipitate
• Bromide = cream precipitate
• Iodide = yellow precipitate