Paper Chromatography

Question 1

chromatography

Answer 1

Chromatography is a chemical analysis technique used to separate substances in a mixture.

Question 2

What is paper chromatography used for?

Answer 2

To separate a mixtures of soluble substances in liquids

Question 3

What is the name given for the pencil line?

Answer 3

The baseline

Question 4

Why should we use pencil for the baseline rather than pen?

Answer 4

Pen ink would dissolve in the solvent and move up the paper

Question 5

Should the baseline be submerged in the solvent?

Answer 5

no

Question 6

What are some solvents commonly used in chromatography?

Answer 6

water, ethanol

Question 7

What is the name of the resulting paper we end up with?

Answer 7

A chromatogram

Question 8

The ‘mobile phase’ refers to the molecules that can move.

Which is the mobile phase in paper chromatography?

Answer 8

the solvent

Question 9

A substance which is more soluble in the mobile phase…

Answer 9

A substance which is more soluble in the mobile phase will spend more time in the mobile phase. This means it will move faster, and travel a further distance up the paper.

Question 10

The ‘stationary phase’ refers to the molecules that can’t move.

Which is the stationary phase in paper chromatography?

Answer 10

the paper

Question 11

A substance which is less soluble in the mobile phase…

Answer 11

A substance which is less soluble in the mobile phase will spend more time in the stationary phase, so move slower, and not travel very far up the paper.

Question 12

The formula to calculate the Rf value:

Answer 12

distance travelled by the substance / distance travelled by the solvent

Question 13

The steps of simple distillation:

Answer 13

1. A solution is heated, usually using a Bunsen burner.
2. The liquid in the mixture evaporates into a gas.
3. The gas is cooled by a water jacket, and condenses into a liquid, which then flows into the beaker.

Question 14

Fractional distillation can separate a mixture of several liquids that each have different:

Answer 14

boiling points

Question 15

order of steps required for fractional distillation

Answer 15

Boiling flask ➔ fractionating column ➔ condenser ➔ beaker

Question 16

Briefly explain the process of fractional distillation to separate a mixture of the liquids methanol, ethanol and propanol.

Answer 16

Heat is applied and the liquid with the lowest boiling point evaporates and condenses into a beaker.

If other liquids evaporate by chance, they condense in the fractionating column back into the flask.

The temperature is altered to repeat the process for the second liquid.

The three liquids are separated based on differing boiling points with the third remaining in the flask.