Distillation: separating a mixture of inks | Combined science

Starter quiz

Which process occurs when a substance changes from the gas state to the liquid state?

evaporation

freezing

condensation ✓

melting
What happens to the boiling point of water when salt is added?

it is lowered

it is raised ✓

it stays the same and is exactly 100°C

it boils across a range of temperatures, e.g. 100 - 104°C ✓
Distillation is a technique that can separate ______ liquids from each other.

'soluble' ✓
Distillation relies upon substances in a mixture having different ______ points.

'boiling' ✓
When heated, which substance listed in the table below would boil first?

pentane

pentene

butane

butylene ✓
Put the statements into the correct order to describe how distillation occurs.

1

⇔

a liquid mixture is heated

2

⇔

the component with the lowest boiling point changes to the gas state

3

⇔

the component in the gas state is collected and moved towards another container

4

⇔

the component in the gas state cools and condenses into its liquid state

Exit quiz

Water soluble liquid ink is found to boil at 105°C-131°C, suggesting it is a mixture of different substances. How might we collect a sample of pure water?

filter

distillation ✓

chromatography

crystallisation
______ is a technique used to separate water from an water-soluble ink solution.

'Distillation' ✓
The component collected at the end of distillation is known as the ...

filtrate.

residue.

mixture.

distillate. ✓
The equipment needed for distillation is lettered on the diagram below. Match each letter to the correct label.

a

⇔

mixture ✓

b

⇔

thermometer ✓

c

⇔

condenser ✓

d

⇔

distillate ✓
What are the limitations of using a simple setup (as shown below) for distillation?

it is difficult to monitor boiling points as there is no thermometer ✓

it is difficult to heat consistently

condensing occurs at the very end, often leading to loss of gaseous component ✓

condensing occurs at the very end, which could be a safety hazard ✓
Some students used the distillation set-up shown. Collection of the distillate could be improved by ...

placing a cold towel around the delivery tube. ✓

heating the mixture more strongly.

placing the test tube into an ice bath. ✓

adding a thermometer.

Worksheet

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Video

Lesson Details

Key learning points

Appropriate equipment should be used to separate substances in a mixture of inks.
Inks are a mixture of substances that can be separated using distillation.
Care should be taken when heating substances to their boiling points.
Simple distillation completed in the school lab has limitations.

Common misconception

Heating a mixture strongly will cause distillation to occur more quickly.

Heating a mixture strongly could cause multiple components to enter a condenser (or delivery tube), resulting in a contaminated distillate. Careful, gentle heating of the mixture to ensure no bubbles near the condenser will reduce contamination.

Keywords

Component - a part of something, e.g. a tyre on a car
Distillation - a separation technique that uses boiling and condensation to remove and isolate a liquid component of a mixture
Delivery tube - a thin tube used to transfer (i.e. "deliver") a substance (usually in the gas state) from one container to another
Condenser - a piece of apparatus composed of a tube surrounded by a cold layer, usually cold water
Distillate - the liquid that is condensed from the gas state during distillation