Recap Separation methods

• Scheikunde
• Middelbare school
• vwo
• Leerjaar 3

Separation methods

Mixtures consist of two or more different substances with different properties. 

Separation method is the technique used for unmixing or separating substances. 

0

Which hazard symbols (GHS-symbols) did you see during the video?

1. explosive
2. toxic
3. flammable
4. harmful

Seperating mixtures (difference to chemical reaction)

Filtration

Seperating base on difference in particle size

Difference in particle size

Filtration

The filtering technique, also known as filtration technique, uses a filter to separate solid particles out of liquid. 

(suspension)

Any solid particles left behind on the filter form the residue and everything that goes through the filter form the filtrate. 

The underlying principle of filtration relies upon the difference in particle size.

 

A few examples of filtration:

• A face mask 
• Sand and water mixture

There are 6 phase transitions. Put the correct description next to each of 6 phase transitions

g → l

s → l

s → g

l → s

l → g

g → s

solidification / freezing

melting

evaporation

condensation

deposition

sublimation

Bezinken en afschenken

Sedimentation and Decanting 

The underlying principle of sedimentation relies upon a difference in density. 

Gravity makes particles with the greatest density slowly sink to the bottom leaving a clear fluid. Once all the particles have sunk you can then carefully decant the clear fluid. 

Sedimentation is often used with great amounts. 

Examples of sedimentation: 

• Sand and water suspension.
• Oil and water emulsion.  

Centrifugation

Difference in density

Centrifugation

In centrifugation, a high-speed rotating motion is used to force substances or particles with a greater density to the bottom. 

It is used to separate suspensions or emulsions. 

Centrifugation is a very sped up version of sedimentation. The underlying principle of centrifugation also relies upon a (small) difference in density 

a few examples of centrifugation: 

• Blood samples in a laboratory. 
• Water in a washing machine. 

Drag all text blocks to the right graph.

Pure substance

Mixture

Melting Point

Boiling Point

Boiling Range

Melting Range

Extraction

Extraction or Extract means to "pull out". Extraction uses an extraction agent to separate mixtures of solid substances.  

The underlying principle of extraction relies upon the difference in the solubility of the substances in a particular extraction medium.  

In the lab a solvent is added

Followed by filtration and evaporation

A few examples of extraction: 

• Making tea or coffee  

Adsorption

Difference in adhesion to solid

Activated carbon used

Removal of colourants, toxins and 
flavourins

Followed by filtration

Adsorption

Adsorption is used to remove a specific substance from a homogeneous mixture. 

This is done using an adsorbent, often activated carbon. 

The underlying principle of adsorption relies upon the difference in adhesion. Adhesion is the ability of substances to stick to each other. 

 

A few examples of adsorption: 

• Norit tablets when u have diarrhea  
• An extraction hood in the kitchen

Difference between absorbtion en adsorbtion

Absorption: substance is taken up by another substance (sponge)

Adsorption only interaction on the surface (norit)

How many liters of water should you add to 125 mL hydrochloric acid with a pH of 3,0 in order to obtain a solution with pH 4,0. (answer in 2 decimals)

What is NOT an example of filtration?

1. Making tea
2. Making coffee
3. Drain pasta
4. Prevent toxins with a gas mask

Evaporation

In Evaporation, you heat up a solution containing a solid dissolved in water. 

 Because of the (great) difference in boiling points the water evaporates leaving the solid substance behind.  

the underlying principle of evaporation is the  (great) difference in boiling points. 

An example of evaporation is:

• Kitchen salt mixture

Distillation

Distilling, also known as distillation, is used to separate homogeneous liquid mixtures in which the liquids have different boiling points.

The difference in boiling points of the two liquids needs to be greater then 20°C.  

 

The underlying principle of distillation relies upon the difference in boiling points. 

An example of distillation: 

• separating alcohol and water out of wine 

Chromotography

At the bottom you add samples on paper (stationairy phase) which is put solvent (mobile phase)

Samples will partially be drawn up with the

liquid

Dots on same height are same substances

Chromatography

Chromatography is used to separate dye mixtures. This is done by using a eluent/ liquid (also known as the mobile phase). 

The underlying principle of chromatography relies upon the solubility of the ink with the eluent and the adhesion of the ink to the stationary phase. 

An example of chromatography:

Ink markers. 

Side by side comparison of the different separation methods. 

Method	Principle	Mixture
Filtration	Difference in particle size	Suspension
sedimentation and decanting	Difference in density	Suspension and Emulsion
Centrifugation	Difference in density	Suspension and Emulsion
Extraction	Solubility
Adsorption	Adhesion	Homogeneous solutions and gas mixtures
Evaporation	Difference in boiling points	Solutions
Distillation	Difference in boiling points	Solutions
Chromatography	Difference in solubility in the eluent and adhesion to the stationary phase.	Ink solutions

What is paper chromotography based on?

1. Difference in boiling points
2. Difference in adhesion to the paper
3. Difference in solubility in the moving liquid
4. B and C

What is not a seperation method?

1. Distillation
2. Chromatography
3. Elektrolysis
4. Filtration

What type of mixture can be extracted?

1. Solution
2. Suspension
3. Emulsion
4. Mixture of solids

What difference in substance properties is adsorption based on?

1. Particle size
2. Adhesion
3. Solubility
4. Boiling point

Making tea:
What separation methods are used?

1. evaporation - filtration
2. evaporation - extraction
3. extraction - evaporation
4. extraction - filtration

Adsorption works ...

1. only with water and gas masks
2. only with water
3. with water, gas masks and fume hoods
4. only with gas masks

How do you seperate a mixture of sand and salt?

1. Decantation, filtration and evaporation
2. Extraction and filtration
3. Extraction, filtration and evaporation
4. Evaporation and filtration

Is sample 3 a pure substance or a mixture?

Is sample 3 a pure substance or a mixture?

1. Pure substance
2. Mixture

What can consist of one kind of molecule?

1. emulsion
2. solvent
3. solution
4. suspension

Filtration is suitable for...

1. homogeneous mixtures
2. heterogeneous mixtures

Drag the name of the mixtures to the most suitable separation method.

filtration

extraction

evaporation

coffee grounds in coffee

stain in trousers

drying wet hair

Filtration and seaving use the same difference in substance properties. Which one?

1. Density
2. Boiling point
3. Solubility
4. Particle size

Can you seperate a solution by filtration?

1. Yes
2. No

What is the mixture called which you can filtrate?

1. Solution
2. Suspension
3. Emulsion
4. Homogeneous

During filtration you get ...

1. residu in the filter
2. residu in the tube
3. filtrate in the filter

What is chromatography?

1. A method for identifying substances in a sample
2. A method for creating new compounds
3. A process of mixing chemicals
4. A technique used to separate and analyze mixtures

Which separation technique is commonly used to separate mixtures of different boiling points?

1. Crystallization
2. Decantation
3. Distillation
4. Sublimation

Which separation technique involves the use of a solvent to separate different components based on their solubility?

1. Decantation
2. Filtration
3. Liquid-liquid extraction
4. Distillation

Centrifugation is a fast form of sedimentation.

1. True
2. False

Which statement best describes the purpose of distillation?

1. To decrease the volume of a liquid.
2. To mix liquids together to create a new substance.
3. To extract solids from liquids.
4. To purify liquids by separating components based on their different boiling points.

What is distillation?

1. A process that separates liquids based on their solubility.
2. A process that separates liquids based on their viscosity.
3. A process that separates liquids based on their melting points.
4. A process that separates liquids based on their boiling points.

Which separation technique is used to separate a solid from a liquid by passing the mixture through a filter paper?

1. Chromatography
2. Centrifugation
3. Filtration
4. Evaporation

What is the product obtained from distillation called?

1. Precipitate
2. Solution
3. Residue
4. Distillate