organic chemistry Flashcards
what is hydrocarbon
any compound that is formed from carbon and hydrogen atoms only
what is a alkane
the simplest type of hydrocarbon you can get
what is the general formula for alkanes
CnH2n+2
Organic chemistry is about molecules that contain which element?
carbon
do alkanes have single or double bonds
only single bonds
what is a homologous series
a group of organic compounds that react in a similar way
what type of series is alkanes apart of
homologous series
what are the first four alkanes
methane,ethane,propane,butane
what is the formula for methane
CH4
what is the formula for ethane
C2H6
what is the formula for propane
C3H8
what is the formula for butane
C4H10
what is the property of a hydrocarbon with a shorter carbon chain
- more runny
- less viscous ( gloopy)
- more flammable
-more volatile ( turn into a gas at a lower temperature) - lower boiling point
what does volatile mean
it means it turns into a gas at a lower temperature
What is the word equation for the complete combustion of a hydrocarbon?
hydrocarbon + oxygen ➔ carbon dioxide + water
During a combustion reaction, are carbon and hydrogen oxidised or reduced?
oxidised
carbon becomes CO2
hydrogen becomes H2O
so both have gained oxygen
Is combustion an exothermic or endothermic reaction?
exothermic
what type of fuel is crude oil
a fossil fuel
what are non-renewable fuels
fuels that take so long to make and their being used up faster than there being formed
what si crude oil
a mixture of hydrocarbons which are mostly alkanes
how can the different compounds be separated in crude oil
through fractional distilation
how is crude oil formed
- dead plants and animals - mainly plankton
- these organic remains buried in the earth
- over millions of years the organic remains were compressed under heat and pressure
- the pressure and heat turns it into crude oil
what are the steps in fractional distillation
- crude oil heated until turned to gas
- gas enter fractionating column
- temperature gradient in column ( hot at bottom cool at hot)
- longer hydrocarbons have higher boiling point so they will condense into liquids first at the bottom, shorter chains of hydrocarbons will condense near the top as it is cooler
- end up with crude oil mixture separated
what are the types of fuel hydrocarbons can be used for
kerosene
petrol
diesel
When separating crude oil we use a fractionating column.
Is the top of the column hotter or cooler than the bottom?
cooler
what is a feedstock
a raw material used to provide reactants for an industrial reaction.
what is a petrochemical
a substance made from crude oil, via chemical reactions.
what is cracking
the process in which larger chain hydrocarbons are split into smaller, more useful hydrocarbons.
why are short chain hydrocarbons more useful than long chain ones
they are more flammable so they make good fuels
What type of reaction is cracking?
thermal decomposition
why is cracking a thermal decomposition reaction?
because it involves using heat to break something apart
what are the different types of cracking
catalytic cracking
steam cracking
what happens in catalytic cracking
- heat the long chain hydrocarbon until it vaporises
- the vapour can be passed over hot powdered aluminium oxide catalyst
- the long chain molecules split apart on the surface of the catalysts
what happens in steam cracking
- heat the long chain hydrocarbon until it vaporises
- mix the vapour with steam and heat them to a very high temperature
-this causes the long chain molecules to split apart
as well as alkanes what else can cracking produce
alkenes
what can alkenes be used for
used as a starting material when making lots of other compounds and can be used to make polymers
do alkanes have a single or double bond
double bond
what does cracking always produce
one alkane and one alkene
does the double bond in alkenes make them more or less reactive
more
what test can be done to test for alkenes?
the bromine water test
what happens when the bromine water test is done on a alkane
no reaction will happen and it will stay bright orange
what colour is bromine water orginally
orange
what will happen when bromine water is added to a alkene
it will result in a colourless compound and the bromine water will be decolourised
why does the bromine water react with alkenes instead of alkanes
because alkenes are more reactive as they have a double bond
How is steam cracking different to catalytic cracking?
there is no catalyst involved in steam cracking
what is the general formula for alkenes
CnH2n
