Hydrocarbons: Alkanes and Alkenes Explained
Alkanes are like nature's straight-chain molecules, following the formula CₙH₂ₙ₊₂. Think methane (CH₄), ethane (C₂H₆), and propane (C₃H₈) - they're saturated hydrocarbons because they can't fit any more hydrogen atoms.
As alkane chains get longer, three key things happen: boiling points rise, they become more viscous (thicker), and they're harder to ignite. This happens because longer chains have stronger intermolecular forces that need more energy to break apart.
Alkenes are the rebellious cousins with double bonds, following CₙH₂ₙ. Ethene (C₂H₄) and propene (C₃H₆) are unsaturated hydrocarbons - they're reactive because of those double carbon bonds.
Quick Test Tip: Drop bromine water on a hydrocarbon - if it stays orange, it's an alkane. If it goes colourless, you've got an alkene!
Crude oil forms when ancient sea creatures decompose under heat and pressure over millions of years. Through fractional distillation, we separate this mixture into useful fractions - short chains (low boiling points) rise to the top of the tower, whilst long chains (high boiling points) stay at the bottom.
Cracking breaks long, less useful hydrocarbons into shorter alkanes and alkenes using high temperatures and catalysts. It's thermal decomposition that gives us more valuable products with higher demand.
