Chemistry Revision Yr 10

Fractional distillation

1) crude oil is a mixture of different hydrocarbons. Hydrocarbons are copounds that contain only hydrogen and carbon atoms.

2) The oil is heated up and evaporates. It enters the column as a gas.

3) The fractionating column is hot at the bottom and cooler at the top. The hydrocarbons travel up the column and condense when they reach a temperature lower than their boiling point. This means that larger hydrocarbons, with higher boiling points condense nearer the bottom.

4) The smaller hydrocarbons stay as gases and rise up the column. Different fractions now condense back to liquids at different levels.

KEY POINT-the hydrocarbon chains become larger as you go down the column

 - longer hydrocarbon chains have higher boiling points as their molecules get tangled up and need more energy before they can seperate out and become gaseous.

Balancing Equations:

- Law of conservation of mass= no atoms are lost or gained in a chemical reaction.

-There must ALWAYS be the same number…