I/GCSE Chemistry: The Alkanes and Alkenes

In I/GCSE Chemistry, we will learn about the alkanes and alkenes.

1) Oily      

2) insoluble    

3) less dense than H₂O, mainly gasses       

4) Insoluble - doesn’t mix with H₂O

Gas: 4 carbon atoms              

Liquid: 4 – 17 carbon atoms              

Solid: 17+ carbon atoms

Hydrocarbons + burning --> Carbon dioxide + water

When there is a lack of oxygen:         Hydrocarbons + burning --> Carbon monoxide + soot

Alkanes don’t react with aqueous reagents e.g. acids or alkali’s.

This is because they are saturated – their C – H and C – C bonds are difficult to break = highly un-reactive.

The formula CnH (2n+2), where n = no of carbon atoms, can be used to determine the formula for each alkane. E.g. To find propane: C₃H (2x3 +2) = C₃H₈

Remember state symbols + balancing the equation

The alkenes are unsaturated and are more reactive b/c of the C =C double bond.

The double bond allows them to melt and form into different things e.g. plastic

You got it now!