Separation of mixtures

Question 1

What is an element?

Answer 1

An element is a substance that contains just one type of atom

Question 2

What is a mixture?

Answer 2

A mixture is made up of two or more different substances that aren’t chemically joined together

Question 3

What is a compound?

Answer 3

A compound is made up of two or more types of atoms that are chemically joined together

Question 4

Write down two types of particles

Answer 4

Atoms and molecules

Question 5

Write an example of an element, a mixture and a compound

Answer 5

Element: Hydrogen
Mixture: Air
Compound: Water

Question 6

Can mixtures be separated and why

Answer 6

Mixtures can be easily separated as they are not chemically joined together

Question 7

What are 4 different methods of separation

Answer 7

Filtration, Evaporation, Simple distillation and chromatography

Question 8

Where can we use filtration

Answer 8

We can use filtration to separate an insoluble solid from a liquid

Question 9

What is an insoluble substance

Answer 9

An insoluble substance is one that does not dissolve in water

Question 10

What is a real-life example of where we can use filtration

Answer 10

We can use filtration to separate sand from water

Question 11

Write down the process of filtration

Answer 11

Firstly, pour the mixture into a filter funnel aligned with some filter paper. The insoluble solid will stay on the filter paper and will be collected as the residue, while the water will pass through and will be collected as the filtrate in the beaker. This is because liquid particles are small and can pass through the filter paper, while the solid particles are bigger and they therefore can’t. Then, the sand is washed and is dried in an oven

Question 12

What is the residue

Answer 12

The residue is the solid left on the filter paper

Question 13

What is the filtrate

Answer 13

The filtrate is the liquid that comes through the filter paper and is collected in the beaker

Question 14

Write one real life use of filtration

Answer 14

Filtration is used in the making of drinking water. Solid impurities are firstly removed using filtration. Then, the water is treated with chlorine to kill microorganisms

Question 15

Where can we use evaporation

Answer 15

Evaporation is good for separating a soluble solid from a liquid

Question 16

Write one example of evaporation

Answer 16

One example of evaporation is separating salt from water

Question 17

Write down the process of evaporation

Answer 17

Pour the solution into an evaporating basin. Heat the evaporating basin until all the water is evaporated, leaving the salt in the basin. This happens because water has a lower boiling point than the salt, so it evaporates first

Question 18

What is indirect heating

Answer 18

Indirect heating is another form of evaporation. A beaker full of water is placed under the evaporating basin. The beaker is heated, which turns water into steam. As the steam rises, it heats the evaporating basin, causing the liquid to evaporate

Question 19

What are the pros and cons of indirect heating

Answer 19

Pros: It is more accurate, as spitting is prevented
Cons: It is more time consuming

Question 20

What is distillation used for

Answer 20

Distillation is used to separate a liquid from a soluble solid or to separate one liquid from another.

Question 21

Write down the process of distillation

Answer 21

The mixture is first placed inside a distillation flask and is heated together with anti-bumping granules to prevent violent boiling. The substance with the lowest boiling point turns into vapour and enters the condenser. In the cold condenser, the vapour is cooled down and is condensed back into a liquid. The pure liquid is then collected as the distillate.

Question 22

What are anti-bumping granules

Answer 22

Anti-bumping granules are small pieces of broken porcelain that prevent violent boiling and help the liquid boil smoothly

Question 23

What are miscible liquids?

Answer 23

Miscible liquids are liquids that mix together

Example: Ethanol and Water

Question 24

What do two liquids have to be in order to be separated

Answer 24

They need to be miscible and to have a difference in boiling temperature of over 30 degrees

Question 25

Write down 6 precautions to achieve the separation with distillation

Answer 25

1: Type of heating: If the liquids are flammable, you should use a water bath or an electric heater to heat the liquids rather than a naked flame
2: Thermometer: The thermometer should be placed at the entrance of the condenser, so that the exact boiling point is recorded
3: Anti-bumping granules: Place pieces of broken porcelain in the mixture to allow it to boil smoothly
4: Connections to the condenser: Water should be coming in at the bottom and going out at the top. This prevents air from being trapped inside the condenser, something that could cause it to crack
5: Collection vessel: The collection vessel should have a small opening to reduce evaporation
6: The apparatus should be open to prevent pressure building up when the apparatus is heated

Question 26

Why is water leaving the condenser hotter than the water entering

Answer 26

Water leaving is hotter because the heated vapour particles that enter the condenser move towards the water since it is colder

Question 27

What is chromatography

Answer 27

Chromatography is a technique used to separate dissolved substances that have different colors

Question 28

What can we identify with chromatography

Answer 28

Chromatography helps identify whether a substance is pure and identify what an unknown sample is

Question 29

Write down the process of chromatography

Answer 29

Place a spot of the mixture on a pencil line at the bottom of the chromatography paper. Put the chromatography paper into a container containing a suitable solvent. The solvent is absorbed and it rises up, causing the different components of the mixture to begin to separate. The different solutes have traveled different distances according to their solubility

Question 30

Why do we draw a line with a pencil on the chromatography paper

Answer 30

We draw the line with a pencil as it is insoluble and it won’t get mixed up when placed in the water