4.8 Chemical analysis (might come up)

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 and how is it made

Answer 2

A mixture of compounds measured in quantities that has been designed as a useful product
Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods
eg alloys are mixtures of metals, they are harder than pure metals so have a particular use

Question 3

How is Rf calculated

Answer 3

distance moved by spot / distance moved by solvent

Question 4

Test for hydrogen

Answer 4

Squeaky pop - burning splint over gas

Question 5

Test for oxygen

Answer 5

Glowing splint relights

Question 6

Test for carbon dioxide

Answer 6

Turns limewater cloudy

Question 7

Test for chlorine

Answer 7

Bleaches damp litmus paper white

Question 8

Flame test for lithium

Answer 8

Crimson red

Question 9

Flame test for sodium

Answer 9

Yellow flame

Question 10

Flame test for potassium

Answer 10

Lilac flame

Question 11

Flame test for calcium

Answer 11

Orange red flame

Question 12

Flame test for copper

Answer 12

Green flame

Question 13

Test for carbonate anions

Answer 13

Add dilute acid

Fizzing observed as CO2 is released

Question 14

describe the test for sulfate anions

Answer 14

Add a solution of BaCl2
White precipitate of BaSO4 formed

can also be a test for barium - add sulfates - white precipitates

Question 15

What are instrumental methods

Answer 15

Accurate. sensitive and rapid methods which are useful when the amount of sample is very small