Tests for cations

Question 1

Lithium flame test

Answer 1

Goes red

Question 2

Sodium flame test

Answer 2

Goes yellow

Question 3

Potassium flame test

Answer 3

Goes lilac

Question 4

Calcium flame test

Answer 4

Goes orange-red

Question 5

Copper flame test

Answer 5

Goes blue-green

Question 6

How to carry out a flame test

Answer 6

1) Clean a platinum wire loop by dipping it into some dilute HCL and holding it in a flame.
2) Once you hold the loop in the flame and it burns without any colour you can do your test.

Question 7

What happens when copper (II) ions are added to sodium hydroxide?

Answer 7

A blue precipitate is formed

Question 8

What happens when iron (II) ions are added to sodium hydroxide?

Answer 8

A sludgy-green precipitate is formed

Question 9

What happens when iron (III) ions are added to sodium hydroxide?

Answer 9

A reddish-brown precipitate is formed

Question 10

How to carry out the sodium hydroxide test

Answer 10

Add a few drops of sodium hydroxide to the chosen ions and see if a coloured precipitate forms.

Question 11

What happens when ammonium compounds are added to sodium hydroxide?

Answer 11

1) Stinky ammonia is given off.
2) You can check for ammonia gas using a damp piece of red litmus paper.
3) If ammonia is present, it will turn blue.
4) This test can be used to determine whether a substance contains ammonium ions. Add some sodium hydroxide to a solution of the mystery substance in a test tube.
5) If ammonia gas is given off, this means ammonia ions are present.