3b.3 - Tests for Positive and Negative Ions

Question 1

What element, when burnt, burns with a crimson flame?

Answer 1

Lithium

Question 2

What element, when burnt, burns with a yellow flame?

Answer 2

Sodium

Question 3

What element, when burnt, burns with a lilac flame?

Answer 3

Potassium

Question 4

What element, when burnt, burns with a red flame?

Answer 4

Calcium

Question 5

What element, when burnt, burns with a green flame?

Answer 5

Barium

Question 6

What metal forms a white precipitate?

Answer 6

Ca2+ and Mg2+

Question 7

What metal forms a blue precipitate?

Answer 7

Cu2+

Question 8

What metal forms a green precipitate?

Answer 8

Fe2+

Question 9

What metal forms a white precipitate at first but redissolves in NaOH to form a colourless solution?

Answer 9

Al3+

Question 10

Which two tests can identify positive metal ions? (2)

Answer 10

• Flame tests

- Coloured precipitate with NaOH

Question 11

How do you test for carbonates?

Answer 11

Bubble it through lime water to check for CO2

Question 12

How do you test for halide ions?

Answer 12

Add dilute nitric acid followed by silver nitrate solution

Question 13

What precipitate does a chloride give? (2)

Answer 13

• White

- Of silver chloride

Question 14

What precipitate does a bromide give? (2)

Answer 14

• Cream

- Of silver bromide

Question 15

What precipitate does a iodide give? (2)

Answer 15

• Yellow

- Silver iodide

Question 16

How do you test for sulphate ions?

Answer 16

Add dilute hydrochloric acid followed by barium chloride solution

Question 17

What would you find if you added hydrochloric acid followed by barium chloride solution to a sulphate?

Answer 17

• White

- Barium sulfate