Flame tests

Question 1

What does a crimson flame indicate?

Answer 1

A lithium ion is present

Question 2

What does a purple/lilac flame indicate?

Answer 2

A potassium ion is present

Question 3

What does a yellow flame indicate?

Answer 3

A sodium ion is present

Question 4

What does an orange/red flame indicate?

Answer 4

A calcium ion is present

Question 5

What does a green flame indicate?

Answer 5

A copper (II) ion is present

Question 6

What are the advantages and disadvantages of flame tests?

in comparison to FES

Answer 6

A

• cheap
• Requires minimal equipment

D
- Colours can be masked if more than one ion is present in the compound
- Colours can be difficult to distinguish, e.g. if there is a low concentration of the
compound

Question 6

What are the advantages and disadvantages of flame tests?

in comparison to FES

Answer 6

A

• Quick and cheap
• Requires minimal equipment

D
- Colours can be masked if more than one ion is present in the compound
- Colours can be difficult to distinguish, e.g. if there is a low concentration of the
compound

Question 7

Describe how FES works

basically

Answer 7

• Sample of metal ion in solution is placed in a flame
• Light given off is passed into a spectroscope
• Spectroscope converts the light into a line spectrum
• Lines in spectrum are specific for each metal ion

Question 8

What can a FES line spectrum tell us?

Answer 8

Which (if any) metal ions are present, as the lines are specific for each metal ion

The concentration of the metal ion, as the lines are more intense at higher concentration

Question 9

Advantages of using FES (INSTRUMENTAL METHOD)

Answer 9

• Automatic and rapid
• More sensitive (quick to detect/respond to slight changes)
• More accurate

Question 10

What are instrumental methods?

Answer 10

Methods that use a machine