Crude Oil and Hydrocarbons

Ever wondered what petrol is made from? It all starts with crude oil, a finite resource buried deep in rocks. This means one day it will run out if we keep using it at current rates. Crude oil forms over millions of years from the remains of tiny sea creatures called plankton.

What makes crude oil special is that it's a mixture of hydrocarbons - molecules made up of only hydrogen and carbon atoms bonded together. The simplest hydrocarbon is methane (CH₄), which has one carbon atom bonded to four hydrogen atoms. Another example is ethane (C₂H₆), with two carbon atoms and six hydrogen atoms.

Scientists classify these types of hydrocarbons as alkanes. They follow a neat formula: CₙH₂ₙ₊₂. This means if you know how many carbon atoms an alkane has (n), you can work out the hydrogen atoms by multiplying by 2 and adding 2. For example, propane has 3 carbon atoms, so it must have 8 hydrogen atoms (3×2+2=8).

Try it yourself! If butane has 4 carbon atoms, how many hydrogen atoms should it have? Apply the formula CₙH₂ₙ₊₂ to find out!