Methods of Separation

What method is used separate a mixture of two liquids and what characteristic property is involved?

1. Fractional Distillation

2. Boiling Point

What method is used to separate two soluble solids and what characteristic property is involved?

1. Fractional Crystallation

2. Solubility at different temperatures

What method is used to dissolve two insoluble solids and what characteristic property is involved?

1. Separation by Floatation

2. Density

What method is used to separate one soluble and one insoluble solid and what characteristic property is involved?

1. Separation by Filtration

2. Solubility in a liquid

 

Pure Substance
Compound or element. A substance that cannot be separated any further. Characteristic properties will remain each time tested.
Mixture
Two or more pure substances combined. Combination of elements and/or compounds not chemically combined (ex. air, saltwater)
Can mixtures be restored after separation?
Some can be restored by simply, but others cannot be restored by just mixing. Also, other cannot be restored in anny way.
Fractional Distillation

1. Heat mixture and record temperature every 30 seconds

2. Plateus in temperature are boiling points and for each boiling point there is a liquid in the mixture this will determine how many fractions will need to be taken

3. Re-heat the mixture and collect the fractions

Fractional Crystalliztion

1. Dissolve solids in water heat mixture boiling away water until precipitate appears

2. Filter through hot filter system

3. Cool the filtrate and crystals sould appear

The residue is the solid with a lower solubility at high temperatures and the filtrate is the solid with a higher solubility at high temperatures.   

Separation by Filtration

1. Place mixture in water and shake.

2. Filter through filter system

3. Boil away water from filtrate

The residue is the insoluble solid and the filtrate with the water boiled away is the soluble solid. 

Separation by Floatation

1. Place the mixture in water and shake

2. Skim the surface of the water to separate one solid

3. Boil away water from the other to separate the second solid

The solid that floated and was skimmed off the surface of the water is the solid with the less density. The solid at that was at the bottom of the container is the solid with a greater density.

How to separate a mixture where substances are dissolved on minute quantities (ink) and what property is involved?

1. Chromotography

2. Molecule Size

How to separate a mixture of gases and what property is involved?

1. Liquefy gases and fractionally distill

2. Boiling Point

Describe how chromotography works

When a solvent moves through capilary action, it ‘drags’ whatever is dissolved in it along with it. The further it moves by capilary action, the slower it goes. So, just as a stream first drops boulders then rocks and finally sand and silt as it slows down, the larger molecules (red) fall out first then the smaller (yellow and green) and finally, the smallest (blue).

[image]

 

Based on this graph how many substances are in this mixture? Which fections contian pure substances? Which fraction has the highest density? (e doesn’t exist)

1. 2

2. b ; d

3. d

What is Petroleum? And how is it separated?
Also;called “crude oil” petroleum is vegetable and animal material decaying;over millions of years. The components of petroleum have;different boiling points, so they can be fractionally distilled.
What is Skimming used for?
Used to separate insoluble solid from liquid if solid is less dense.
What is decanting used for?
Used to separate insoluble solid from liquid if solid is more dense.
Residue
Insoluble Solid
Filtrate
Soluble Solid
Steps of fractional crystallization

1. Place solid mixture in 2.5X the amount of water

2. Heat until 1/2 the water is gone and precipitate appears

3. Filter at 70C or higher (hot filter)

4. Dry solids and do quantitative tests;

How much of air is nitrogen and what is its boiling point? How much of air is oxygen and what is its boiling point?

1. 80% 196C

2. 20% 183C

One air is liquified it can be fractionally distilled into separate gases.

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