ORGANIC CHEMISTRY Flashcards
What is a hydrocarbon?
Any compound that contains only hyrdogen and carbon atoms.
What is the formula for an alkane?
2n+2
What type of bonds do alkanes have?
Single bonds.
Why do alkanes have single bonds?
Because they are saturated.
How many bond does a carbon atom have to have in an alkane?
4 single bonds.
What are the first four alkanes?
Methane
Ethane
Propane
Butane
What happens when the length of a carbon chain is short?
The hydrocarbon is runny (less viscous)
Lower boiling point
More flammable
What is the equation for complete combustion with hydrocarbons?
hydrocarbon + oxygen –> carbon dioxide + water
What happens during combustion?
Both carbon and hydrogen from the hydrocarbon are oxidised.
Why are hydrocarbons used as fuels?
Because they release large amounts of energy when combusted completely.
Why are alkanes saturated?
Because they contain single bonds so they cannot hold anymore hydrogen atoms.
What do you use to test whether something is an alkane or alkene?
Bromine water.
How do you know if something is an alkane?
When added to bromine water, the solution stays orange
How do you know if something is an alkene?
When added to bromine water, the solution turns colourless.
Why does bromine water stay the same colour (orange) when added to an alkane?
When an alkane added to bromine water, there is no spare bonds so the bromine water is unable to bond so no reaction occurs therefore it stays orange.
Why does bromine water change colour (to colourless) when added to an alkene?
Because bromine reacts with the alkene as it is unsaturated (has a spare bond)
What type of bonds does carbon have in alkenes?
Double bond.
What is the formulae for alkenes?
CnH2n
Why do alkenes have double bonds?
Because they are unsaturated.
Why are alkenes unsaturated?
The double bond between the carbon atoms can open up to make two single bonds allowing the two carbon atoms to bond with other atoms.
Why are alkenes reactive?
Because they have double bonds that can be split open to react with other atoms.
What are the first four alkenes?
Ethene
Propene
Butene
Pentene
Why is there no methene?
Because you have to have at least two carbons because there needs to be a double bond in between then.
Why can alkenes not combust completely in the air?
Because there is not enough oxygen so therefore they undergo incomplete combustion.
What is the equation for incomplete combustion with alkenes?
alkene + oxygen –> carbon + carbon monoxide + carbon dioxide + water
What flame does incomplete combustion result in?
A yellow smoky flame.
What happens when alkenes are reacted with steam?
Water is added and an alcohol is formed.
What can alkenes react with apart from steam?
Halogens such as bromine, chlorine and iodine.
What are alcohols (symbol wise)?
-OH
What is a homologous series?
A family of organic compounds with the same functional group
What is a hydroxyl group?
-OH (alcohols)
What are the first four alcohols?
Methanol
Ethanol
Propanol
Butanol
What is the formula for alcohols?
2n+1 + OH
How do alcohols undergo complete combustion (word equation)?
alcohol + air —> carbon dioxide + water