Test For Ions

Question 0

If more sodium hydroxide is added and the white precipitate dissolves what ions is present? If the precipitate doesn’t dissolve then what ions are present?

Answer 0

If the precipitate dissolves then Al3+ ions are present. If the precipitate does not dissolve then either Ca2+ ions or Mg2+ ions are present.

Question 1

What ions are present if sodium hydroxide is added to a solution and a white precipitate forms?

Answer 1

Al3+, Ca2+ or Mg2+

Question 2

What ion is present if you add sodium hydroxide is added and a green precipitate is formed?

Answer 2

Fe2+

Question 3

What ion is present if you add sodium hydroxide is added and a brown precipitate is formed?

Answer 3

Fe3+

Question 4

What ion is present if sodium hydroxide is added and a blue precipitate is formed?

Answer 4

Cu2+

Question 5

If you know you have Ca2+ or Mg2+ because the white precipitate didn’t dissolve when more Sodium Hydroxide was added, what test can you use to know which ion is present?

Answer 5

Flame test- if it burns brick red it’s Ca2+ and if you doesn’t burn a colour it’s Mg2+

Question 6

What test can you use to check if negative carbonate ions are present?

Answer 6

1.add a dilute acid to the carbonate and it fizzes and gives off carbon dioxide 2.bubble the gas given off through lime water 3. If the gas which is given off is carbon dioxide, then a white precipitate of calcium carbonate is formed in the lime water

Question 7

What is the test to see if halide ions are present in a solution?

Answer 7

1.add dilute nitric acid 2.add silver nitrate 3. A precipitate is formed

Question 8

In the Hallide test which ion is present if the precipitate formed is white?

Answer 8

Silver chloride (presence of Cl-)

Question 9

In the halide test which ion is present if the precipitate formed is cream?

Answer 9

Silver bromide (presence of Br-)

Question 10

In the Halide test which ion is present if a yellow precipitate is formed?

Answer 10

Silver iodide (presence of I-)

Question 11

What is the test to see if sulphate ions are present?

Answer 11

1.add dilute hydrochloric acid 2.add barium chloride solution 3. White precipitate formed if sulphate ions are present (SO42-)

Question 12

Why should only nitric acid be used for halide ion test?

Answer 12

Because other acids would form a white precipitate with the silver nitrate. Making the results not valid.

Question 13

Why should you not add sulphuric acid to the sulphate ions?

Answer 13

Because it contains sulphate ions

Question 14

In the sulphate test why do you add hydrochloride acid before the barium chloride?

Answer 14

To remove any carbonate ions which would otherwise form a white precipitate.