Separation of mixture techniques

Question 1

Sieving/ screening:

Answer 1

• Separates solids based on their different particle size

- Smaller particles pass through a sieve but larger particles are retained

Question 2

Magnetism:

Answer 2

• Separates certain substances based on their ferro magnetic properties
  e. g. iron fillings and sand

Question 3

Ferro- magnetism:

Answer 3

Refers to the ability of a substance to be naturally attracted to a magnet.

Question 4

Sedimentation:

Answer 4

Separates a solid from a liquid/ gas phase based upon the solid’s higher density
e.g. tea leaves settling in tea

Question 5

Decanting:

Answer 5

• Used to separate an insoluble solid from a liquid
• Because once the solid has settled, top layer of liquids can be removed

NOTE: this process does not completely separate all liquids from liquids and works if the solids are sufficiently dense

Question 6

Filtration:

Answer 6

Filtration can be used to separate:

• a liquid and a solid
• a soluble solid mixed with an insoluble solid
• Water is added to dissolve the insoluble solid
• Insoluble solid caught in filter paper is called residue
• Substance passing through filter paper is filtrate

Question 7

Evaporation:

Answer 7

• Used to separate a mixture containing a liquid with a dissolved/ undissolved solid
• The liquid evaporates, leaving the solid residue
• Uses the property of the two difference in boiling points between the solid and liquid
• Uses the property of the difference in boiling points between the solid and liquid

Question 8

Distillation:

Answer 8

• Separates a mixture of two miscible liquids
• Miscible liquids dissolve in one another, to form homogeneous solutions
• Can also be used to separate a mixture containing a liquid with a dissolved solid
• Use the property of large difference in boiling point between components

When the mixture is heated, the more volatile (easily evaporated at normal temperatures) component evaporates and passes through a condenser

• the gas is condensed back into liquid and is collected as distillate
• the less volatile is left behind as residue

Question 9

Fractional distillation:

Answer 9

• Used to separate miscible liquids with a small difference in boiling points
• The arrangement of the fractioning column allows for repeated condensation and vaporisation to effectively distil components
• can also separate a mixture of gases

Question 10

Separating funnel:

Answer 10

Used to separate a heterogeneous mixture of 2 or more immiscible liquids
- More dense liquids will sink to bottom
- Less dense liquids will float to the top
Liquids are separated based on density

Question 11

Gravimetric analysis:

Answer 11

Involves quantitative analysis of the mass of substances

• Percentage of components in a mixture
• Percentage composition of elements in compounds