C7 Flashcards
what is hydrocarbons?
what is alkane and formula?(2)
what are the first 4 alkanes and how do you draw them?
Mnemonic?
-Hydrocarbon is any compound that is formed from carbon and hydrogen atoms only
-Alkanes are saturated compounds and they are a homologous series (react in a similar way)
-Formula is CnH2n+2
First 4 alkanes are:
-methane=ch4
-ethane=C2H6
-propane=C3H8
-butane=C4H10
-You draw them by how much CS they are you put H with and arrow poking out
MICE EAT PAPER BAGS
why does hydrocarbon properties change?
what happens when the chain is shorter?(3)
why does properties of hydrocarbon affect how they’re used for?
-They change as the chain gets longer
SHORTER CHAIN:
=less viscous (more runny)
=more volatile (lower boiling point)
=more flammable (easier to ignite)
-Because eg short chain hydrocarbons with lower boiling points are used as bottled gasses,also they are used for fuels due to the amount of energy released when they combust completely
when does complete combustion occur?
what are the waste products?
what happens during combustion?
what is the combustion equation?
-Occurs when any hydrocarbon in oxygen releases lots of energy
-Waste products are carbon dioxide and water vapour
-During combustion both carbon and hydrogen from the hydrocarbon are oxidised
Hydrocarbon+oxygen=carbon dioxide+water
what is crude oil where is it formed?
what are examples of non-renewable (fossil fuels)?and what are they resources of?
-Crude oil is a fossil fuel.Its formed from the remains of plants and animals mainly plankton that died millions of years ago and were buried in mud.Over million of years with high temperature and pressure, the remains turned to crude oil which can be drilled up from the rocks where it’s found
-Examples of non renewable is like coals,oil and gas as they take so long to make that they’re being used up much faster than they’re being formed.They’re finite resources one day they will run out
what can be used to separate hydrocarbon fractions?
what is crude oil a mixture of?
what are the 4 steps of how they can be separated?
-Fractional distillation can be used
-Crude oil is a mixture of lots of different hydrocarbons
1)The oil is heated until most it turns into gas.The gases enter a fractionating column
2)In the column there’s a temperature gradient (hot st the bottom and gets cooler as you go
3)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 point.They condense and drain out much later on near the top of the column where it’s cooler
4)You end up with the crude oil mixture separated into different fractions.Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms so have similar boiling points
