Organic Chemistry Flashcards
What is a hydrocarbon made out of?
- carbon
- hydrogen
what is the simplest type of hydrocarbon?
general formula?
- alkanes
- CnH2n+2
- homologous series
- saturated compound
what are the first four alkanes?
- methane
- ethane
- propane
- butane
explain how properties of hydrocarbons are affected?
- shorter carbon chain
- less viscous
- more volatile (lower bpt)
- more flammable
how do properties of hydrocarbons affect how they are used for fuels?
- short chain hc w/ lower bpt are used as bottled gases
- stored under pressure as liguids in bottles
what is complete combustion of hydrocarbons?
why is it used?
- both carbon and hydrogen oxidised
- waste products are CO2 and water
- hc used as fuels as release lots of energy when combust completely
why are fossil fuels non-renewable?
- used up fatser than being produced
- finite so will run out
how is crude oil seperated using industrial fractional distillation?
- oil heated until most gas and enter fractionating column
- column has temp gradient
- long hc have high bp, condense first at bottom where its hot
- short hc have low bp, condense drain out later near the top where its cooler
- mixture sperayed into different fractions: similar carbon atoms/bp
what fractions of hc are used for different fuels?
3: LPG
8: petrol
15: kerosene
20: diesel oil
40: heavy fuel oil
what do petrochemical industry use hc for?
- feedstock to make new compounds for
- polymers
- solvents
- lubricants
- detergent
what is organic compounds?
why is there a large variety of them?
- contain carbon atoms
- bond together to form different homologous series
why do short chain hc make good fuels?
why not long chain?
- flammable
- high in demand
- long chain form thick gloopy tar
why is cracking used on long chain hc from fractional distillation of crude oil?
-make smaller, more useful hc
what are the products of cracking?
- alkane
- alkene used as starting material for polymers
what reaction is cracking?
- thermal decomposition reaction
- break molecules down by heating
what is catalytic cracking?
- heat long chain hc to vaporise
- vapour passed over hot-powered aluminium oxide catalyst
- long chain hc split apart on surface of specks of catalyst
what is steam cracking?
- heat long chian hc to vaporise
- mix vapour with steam
- heat to very high temp
what are alkenes?
general formula?
reactivity?
- hc with C=C
- unsaturated
- CnH2n
- C=C open to single bond so carbon can bond with other atom making it more reactive than alkanes
what are the first four alkenes?
- ethene
- propene
- butene
- pentene
why do alkenes not combust completely?
what are the products?
- not enough oxygen in air
- incomplete combustion
- smoky yellow flame
- less energy
- produce CO or C
what is a functional group?
- group ofatoms in molecule
- determines how typically reacts
how do alkenes react generally?
- addition reactions
- C=C opens up and new atom added to single bonds