C8 - Chemical Analysis

Question 1

What is a pure substance in
chemistry?

Answer 1

A pure substance is only made from a
single element or compound. It is not
a mixture

Question 2

What are the fixed points
of a substance?

Answer 2

The fixed points of a substance
are the melting and boiling points

Question 3

How do impurities affect the fixed points?

Answer 3

Impurities lower the melting point and raise the boiling point

Question 4

What is a formulation?

Answer 4

A formulation is a mixture that has
been designed as a useful product.
Formulations are made by mixing the
components in carefully measured
quantities to ensure that the product
has the required properties

Question 5

Why do some dyes move further up
chromatography paper than others?

Answer 5

Some dyes are more attracted to the
mobile phase. This means they will move
up the paper.
The more attracted to the mobile
phase the further up the dyes go

Question 6

What is the equation for
retention factor Rf?

Answer 6

Retention factor = distance moved by substance ÷ distance moved by solvent

Question 7

What is the test for hydrogen?

Answer 7

Place a lighted splint in the gas.
Hydrogen gas will make a squeaky
pop

Question 8

What is the test for oxygen?

Answer 8

Place a glowing splint in the gas.
If the gas is oxygen the glowing splint
will relight

Question 9

What is the test for carbon dioxide?

Answer 9

Bubble the gas through limewater.
If the gas is carbon dioxide the limewater will turn cloudy.

Question 10

What is the test for chlorine?

Answer 10

Put damp blue litmus paper in the gas.
If the gas is chlorine it will turn the
blue litmus paper white.