Separating Mixtures

Question 1

What Is fractional distillation and how does it work

Answer 1

• it separates a liquid from a mixture of liquids
• when you heat up the mixture, one of the liquids will evaporate and move up the each fractioning column, stopping on each level, eventually, the liquid with the lowest boiling point will evaporate and the process will continue until all of the liquids have been evaporated and separated

Question 2

What is simple distillation and how does it work

Answer 2

• separates a solvent from a solution
• the solution is heated until the solvent evaporates, the gas is collected and then is condensed in the cooling chamber, where it is then collected in a Beaker

Question 3

Crystallisation

Answer 3

• it separates a solute form a solvent
• produces a dry sample of the solute
• works by heating the solution up until the solvent evaporates, leaving the solute behind

Question 4

What is filtration

Answer 4

• Separates an insoluble solid from a liquid
• filter paper lets through liquid as filtrate
• the insoluble solid substance left over forms residue

Question 5

What are the two phases in chromatography

Answer 5

• stationary phase = paper (in paper chromatography it is the silica that it is coated in)
• mobile phase = the solvent

Question 6

What does it mean if the substance travels up very high in paper chromatography

Answer 6

It means that the substance has high bonding with the mobile phase (the solvent). If it does not move up that high, it means it has a higher bonding with the stationary phase.

Question 7

What are the mobile phase and stationary phase in gas chromatography and TLC

Answer 7

In gas chromatography, the

• mobile phase is the gas, which is also used as the solvent.
• stationary phase is the silica gel which coats the inside chamber

In TLC, the

• mobile phase is the solvent that the paper is suspending in
• the stationary phase is the silica gel that coats the paper

Question 8

How to calculate RF value

Answer 8

Rf = distance travelled by substance / distance travelled by solvent

Question 9

In distillation, where does the water in the condenser enter the condenser

Answer 9

Water goes in through the tap lower down the condenser

Question 10

Why is the line not drawn in ink in paper chromatography

Answer 10

The ink may dissolve in the solvent

Question 11

What are similarities
and differences between gas chromatography and TLC

Answer 11

Similarity - both use silica in the stationary phase

Difference - use different states as solvents