Flame tests

Question 1

Why do these metal salts give off a characteristic colour?

Answer 1

Since each element has its own electron configuration this means that each element has different electron transitions and thus characertistic colour

Question 2

How could you determine what metal is contained in an unknown substance

Answer 2

Hold the salt in the blue flame of the Bunsen Burner and observe the colour given off. Compare this colour with the standard colours given off my different metals

Question 3

How would you prevent cross contamination?

Answer 3

Use a new disposable wooden splint for each salt tested

Question 4

Why is a damp wooden splint used to hold the salt?

Answer 4

It does not give off a colour that would interfere with the characteristic colour emitted by the salt

Question 5

Give one practical application of flame tests

Answer 5

To identify the presence of certain metals

Question 6

KCl, KNO3, Na2HPO4.12H2O,Na2SO3.7H2O, NaHCO3 and Na2SO4.10H2O.
Describe how the student could have distinguished between the samples that contained potassium
ions and those that contained sodium ions using the flame test technique.

Answer 6

Introduce salt into flame of bunsen burner using soaked wooden splint
sodium (Na) gives yellow flame
potassium (K) gives lilac flame