Organic Chemistry Flashcards
What is a hydrocarbon
Any compound formed from carbon and hydrogen atoms only
What are alkanes
- formula CnH2n+2
- in homologous series
- saturated compounds
What’s the homologous series
A group of organic compounds that react in a similar way
What is a saturated compound
Means that each carbon forms 4 single covalent bonds
What are the 4 first alkanes
- methane CH4
- ethane C2H6
- propane C3H8
- butane C4H10
How does length of carbon affect the properties of hydrocarbons
- shorter carbon chain: more runny, less viscous(gloopy)
- shorter carbon chain: more volatile (lower boiling point)
- shorter carbon chain: more flammable
Word equation for complete combustion of a hydrocarbon
Hydrocarbon + oxygen — carbon dioxide + water + (energy)
Important things that happens during combustion of hydrocarbon
- both carbon and hydrogen atoms are oxidised
- hydrocarbons are used as fuels due to the amount of energy realised wen they combust completely
What is crude oil
- fossil fuel
- can be used to make loads of useful things such as fuels
How is crude oil formed
- formed from remains of plants and animals, mainly plankton that died millions of years ago and were buried in mud
- over millions of years with high temperature and pressure, the remains turn to crude oil
- it can be drilled up from the rocks where its found
How does fractional distillation of crude oil work
- Oil is heated until most of it has turned into gas. The gases enter a fractionating column
- In the column theres a temperature gradient (hot at bottom and gets cooler as you go up)
- The longer hydrocarbons have high boiling points, they condense back into liquids and drain out of the column early on when they’re near the bottom.
- The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near to the top of the column where its cooler
- You end up with crude oil mixture separated out into different fractions. Each fraction contains a mixture of hydrocarbons that al contain a similar number of carbon atoms, so have similar boiling points
Order of different fuels produce from crude oil in a fractionating column
From bottom to top (hot to cold)
- bitumen
- heavy fuel oil
- diesel oil
- kerosene
- petrol
- LPG
What is LPG used for
- liquified petroleum gas
- contains mainly propane and butane
What is petrol used for
Cars
What is kerosene used for
Planes