1
Q
Mixture
A
- A mixture is made up of components not chemically combined together, e.g. ink, fizzy drinks, mineral water, crude oil, air.
2
Q
Mixtures continued…
A
- The components of a mixture can be separated by several methods or techniques.
- Each separation technique makes use of differences in the physical properties of the components.
3
Q
Methods of Separating Mixtures
A
- Magnet
- Filter
- Decant
- Evaporation
- Centrifuge
- Chromatography
- Distillation
4
Q
Magnetic Attraction
A
- Used to separate magnetic materials, e.g. iron, steel, nickel, cobalt from non-magnetic ones in a mixture.
e. g. separating iron filings from sulphur powder
5
Q
Applications of Magnetic Attraction
A
- Electromagnets are used to remove steel and iron scrap at the junk-yard.
- In hospitals, magnets are often used to remove iron splinters from a patient’s eyes.
6
Q
Evaporation to Dryness
A
- Used to separate a dissolved solid (solute) that does not decompose on heating from a solution.
e. g. common salt from a salt solution
7
Q
Procedure of Evaporating a Solution
A
- Pour the solution into an evaporating dish.
- Heat the solution to dryness to evaporate away the solvent, leaving behind the solute.
- Make the Bunsen flame smaller when almost all the solvent has been evaporated away to reduce spitting.
8
Q
Applications of Evaporation
A
- drying wet clothes
- drying hair with a hair dryer
- obtaining common salt from the sea
9
Q
Crystallization
A
- Process to obtain a solid that decomposes on heating from its solution.
e. g. sugar crystals from sugar solution and copper(II) sulfate crystals from copper(II) sulfate solution
10
Q
Filtration
A
- Separates a liquid from a solid.
11
Q
residue
A
- insoluble solid that remains on the filter paper
12
Q
filtrate
A
- liquid that passes through
filtrate can be water, any other solvent, or a solution
13
Q
Applications of Filtration
A
- hair in our nostrils
- trap the dust particles that we breathe and allow only clean air to pass through
- air filters in air conditioners
- remove solid impurities from air
- oil and air filters in cars
- remove solid impurities found in engine oil and air
14
Q
Simple Distillation
A
- Process used to separate a pure liquid (solvent) from a solid-liquid solution.
e. g. pure water can be distilled from soft drinks, sea water, etc.
15
Q
Distillation Apparatus
A
- The solution is boiled and steam is driven off.
- Salt remains after all water is boiled off.
- No chemical change occurs when salt water is distilled.
16
Q
Fractional Distillation
A
- Process can be used to separate miscible liquids with different boiling points.
- Liquid with lower boiling point will vaporize first.
e. g. to separate alcohol and water
17
Q
Industrial Applications of Fractional Distillation
A
- oil refineries
- separating the various components of crude oil or petroleum
- industrial supplying oxygen to hospitals, shipyards, etc.
- separating the components of air
18
Q
Paper Chromatography
A
- Process used to separate the different components in a liquid mixture.
For example it can be used
1. to separate the different colored components that make up black ink
2. to detect tiny amounts of drugs or certain other chemicals in urine samples
19
Q
Applications of Paper Chromatography
A
- analyzing ink dyes for forgery cases
- analyzing food dyes to ensure that only permitted colorings are used in foodstuffs
- checking whether pesticides on vegetables exceed safe levels
- detecting trace levels of drugs in urine samples
20
Q
Centrifugation
A
- Spin sample very rapidly: denser materials go to the bottom (outside)
- Separate blood into serum and plasma
- Plasma = less dense
- Erythrocytes = red blood cells
- Check for anemia (lack of iron)
21
Q
Applications of Centrifugation
A
- It is used for:
- Separating cream from milk and butter from curd in dairies or at home.
- In washing machines to squeezing out water from wet clothes.
- In diagnostic laboratories for testing blood/urine.
22
Q
Separating Funnel
A
- When two immiscible liquids are mixed together they eventually form layers, if left to stand. The less dense liquid forms a layer above the more dense liquid.
23
Q
Decantation
A
- Beaker x2
- Sand
- Water
- Glass rod
24
Q
What is Sieving?
A
- Is used for separating coarse from fine parts of loose matter.
25
What is Straining?
- It is to pour a mainly liquid substance through a porous device or material in order to separate out any solid matter.
26
What is Winnowing?
- Is separating the chaff from the grains by wind.
27
Why do we put filters in our faucets?
A. To separate the impurities from water
B. To purify the water
C. To kill the germs in the water
A. To separate the impurities from water
28
```
If you were given a mixture of sulphur and iron filings, how will you separate the two kinds of components?
A. Use a mirror
B. Use a magnet
C. Use a Bunsen burner
D. Either a or b
```
B. Use a magnet
29
```
You accidentally drop a box of pins on sandy ground. What is the fastest way of recovering the pins from the ground?
A. Use a water heater
B. Use magnet
C. Throw water on the ground
D. Use a filter paper
```
B. Use magnet
Separation Techniques
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