Testing for Metal and Non-Metal ions-PAPER2

Question 1

What colour is the flame for lithium?

Answer 1

Lithium= Crimson

Question 2

What is the flame colour for potassium?

Answer 2

Potassium= Lilac

Question 3

What is the flame colour for Sodium?

Answer 3

Sodium- Yellow

Question 4

What is the flame colour for the Copper ion ?

Answer 4

Copper-Green

Question 5

What is the flame colour for calcium?

Answer 5

Calcium= Orange-red

Question 6

What are these flame tests used for?

Answer 6

To detect metal ions

Question 7

What are some problems with flame tests?

Answer 7

The colour of the flame test can be difficult to distinguish especially if there is only a low concentration of the metal compound.
Also a sample could contain a mixture of metal ions which would mask the colour of the flame, e.g. sodium (yellow) usually masks the colour of any other ion present.

Question 8

What is flame emission spectroscopy?

Answer 8

A sample of the metal ion is place into the flame but then the light given out is then passed through a machine called a spectroscope which then converts the light into a line spectrum.

Question 9

Why is flame emission spectroscopy more accurate than just a human’s judgement?

Answer 9

Because the light is passed through a machine to determine the whereabouts on the line spectrum and using these lines you can then detect which metal ions are present as they are specific to the metal ions.

Question 10

What is an advantage of using an instrumental method?

Answer 10

Instrumental methods are more rapid, they are sensitive.and more accurate.

Question 11

What do you do when testing for a carbonate ion?

Answer 11

Add dilute acid to the sample
The acid will react with the carbonate to make carbon dioxide. The mixture will fizz however this doesn’t prove CO2 was made.
NOW we bubble the gas through lime water. If it goes cloudy then this means we have Carbon dioxide therefore we started with the carbonate ion.

Question 12

How do you test for halide ions

Answer 12

1- Add dilute nitric acid to the sample
2- Add dilute silver nitrate solution.
3-Halide ions produce and precipitate of the silver halide
Each halide makes a different coloured precipitate.

Question 13

What are halide ions?

Answer 13

Chloride, bromide and iodide.

Question 14

What colour precipitate of silver chloride will the mixture turn if chloride ions are present?

Answer 14

White

Question 15

What colour precipitate of silver bromide will the mixture turn if bromide ions are present?

Answer 15

Cream

Question 16

What colour precipitate of silver iodide will the mixture turn if iodide ions are present?

Answer 16

Yellow

Question 17

How to test for a sulfate ion?

Answer 17

Add dilute hydrochloric acid to our sample
then add barium chloride solution
If sulfate ions are present we will see a WHITE precipitate.