Chemistry Topic 8 - Chemical Analysis

Question 1

What is a pure substance?

Answer 1

A pure substance is a single element or compound, not mixed with any other substance

Question 2

What is a formulation?give some examples

Answer 2

A formulation is a mixture of compounds in measured quantities that has been designed as a useful product.
Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.

Question 3

How is Rf calculated?

Answer 3

Distance moved by the spot/distance moved by solvent

Question 4

Describe the tests for hydrogen, oxygen, carbon dioxide, and chlorine

Answer 4

Hydrogen-pop with burning splint over gas
Oxygen-glowing splint relights
Carbon dioxide-turns limewater cloudy
Chlorine-bleaches damp litmus paper and makes it white

Question 5

Describe the flame test result

Answer 5

Lithium compounds-crimson red
Sodium compounds-yellow
Potassium compounds-lilac
Calcium compounds-orange/red
Copper compounds-green

Question 6

What are instrumental methods?

Answer 6

They are accurate, sensitive and rapid methods which are useful when the amount of sample is very small

Question 7

What are cations and anions?

Answer 7

Cations are the positive ions; anions are the negative ions