When crude oil is put through the process of fractional distillation, various hydrocarbons are pumped out. A few hydrocarbons, the temperature at which they condense, the number of carbon atoms in their chain and their uses are as follows -
  • Bottled gas - 3 carbon atoms. No set temperature for condensing, just rolls out of the top of the fractioning tower.
  • Petrol - 8 carbon atoms, comes off at 40 degrees. Used for automobile fuel.
  • Naphtha - 10 carbon atoms, comes off at 110 degrees. Used for high-temperature cracking in chemical production.
  • Kerosine - 15 carbon atoms, comes off at 180 degrees. Used as jet fuel.
  • Diesel - 20 carbon atoms, comes off at 250 degrees. Used as automobile fuel.
  • Oil - 35 carbon atoms, comes off at 340 degrees. Used as lubrication.
  • Bitumen - 40 carbon atoms, used for tarmac.

Using hydrocarbons

As the size of the hydrocarbon chain increases -
  1. The boiling point increases.
  2. It gets less flammable.
  3. It gets more viscous.
  4. It gets less volatile. The vapours of the more volatile hydrocarbons are very flammable, which is why smoking in petrol stations is a bad idea.

Complete combustion of hydrocarbons - safe

When a hydrcocarbon combusts safely, it burns with a blue flame. The equation for complete combustion is -

hydrocarbon + oxygen -> carbon dioxide + water (+ energy)

The two waste products here are perfectly safe.

Incomplete combustion of hydrocarbons - unsafe

If there isn't enough oxygen available, incomplete combustion takes place. The equation here is -

hydrocarbon + oxygen -> carbon dioxide + water + carbon monoxide + carbon (+ energy)

This leaves a tell-tale, sooty deposit of carbon. This is a clue the fuel is not burning fully. Carbon monoxide is a deadly gas which is colourless and odourless.

Hy`dro*car"bon (?), n. [Hydro-, 2 + carbon.] Chem.

A compound containing only hydrogen and carbon, as methane, benzene, etc.; also, by extension, any of their derivatives.

Hydrocarbon burner, furnace, stove, a burner, furnace, or stove with which liquid fuel, as petroleum, is used.


© Webster 1913.

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