Fractional Distillation of Air
Air is made up of:
- 78% Nitrogen
- 21% Oxygen
- 0.04% Carbon Dioxide
- 0.9% Argon
How is air separated?
Liquid air goes in at -200c.
Water is frozen in the cooling unit at 0c.
Carbon Dioxide freezes at -79c.
The oxygen in the air boils (turns into a liquid) at -183c.
The nitrogen in the air boils at -196c.
At the bottom of the tower, it is -185c.
Nitrogen turns into a gas when in the tower because -185c is above it's boiling point. It travels to the top of the tower.
Most of the oxygen stays as a liquid as -185c is below it's boiling point, and is piped out at the bottom.
Separating Immiscible Liquids
Separating Miscible Liquids
To separate immiscible liquids, you can use a separating funnel.
Method
The liquid with the lowest density is at the top. In this example, oil is less dense than water.
Miscible liquids can be separated using Fractional Distillation, but this only works if the two liquids in the mixture have different boiling points.
How?
- The mixture is heated, and the vapours pass into the fractionating column.
- As the gases cool, the ones with the highest boiling points condense first.
- Different liquids are collected at different places at the bottom.
Place the mixture in the funnel with a beaker underneath.
Open the tap until most of the lower liquid has run into
the beaker.
Put a clean beaker underneath and run the last bit of the
lower liquid and a little bit of the top liquid into the beaker.
Place a final clean beaker under the tap and run off all the second liquid.
Miscible or Immiscible?
Miscible liquids mix completely with each other.
Immiscible liquids do not mix completely
with each other.
Additional Chemistry Revision
Miscible and Immiscible Liquids