C1.4 Crude Oil and Fuels

Crude Oil

Crude oil is a mixture of lots of different hydrocarbons. Hydrocarbons are compounds which only contain hydrogen and carbon.

Some of these hydrocarbons are very small such as methane (CH4). This has a very low boiling point and is very flammable. As the hydrocarbons get bigger in size their boiling point increases and they become less flammable.

Fractional Distillation

• Crude oil is heated to 350°C
• Most of the substances in the crude oil are evapourated
• It is pumped into the bottom of a factioning tower
• Heavier hydrocarbons are already liquid or condense
• Smaller hydrocarbons (low bpt.) rise up the tower
• As hydrocarbons are cooled to their bpt. , they condese
• Some hydrocarbons (low bpt.) are collected as gases

Alkanes

• Hydrocarbons
• Short chain ones are more useful as fuels
• Their general formula is CnH2n+2 (where n=no. of carbons)
• The carbon - carbon bonds in alkanes are all single covalent bonds
• This means they are saturated hydrocarbons
  • only have c-c single bonds
  • carbon atoms already have bonds to 4 other atoms so it's not possible to bond to new atoms

Combustion

Combustion is…