C7 Flashcards
What is a hydrocarbon
It is a molecule made up of only hydrogen and carbon atoms
What is an alkane?
. Type of hydrocarbon
. Formula CnH2n+2
. Saturated- each carbon atom forms. 4covalent bond
. First 4 are methane, ethane, propane, butane
What happens to hydrocarbons as they get longer?
Properties change-
. The shorter, the more runny it is
. The shorter, the lower boiling point it will have
. The shorter, the more flammable it is
When does complete combustion occur?
When there is plenty of oxygen
What is the equation for complete combustion and what occurs in complete combustion?
Equation-
Hydrocarbon + oxygen –> carbon dioxide + water
. Releases alot of energy
. During combustion, both hydrogen and carbon from hydrocarbon are oxidised
. Hydrocarbons are used as fuels due to the amount of energy they release when cumbust completely
How is crude oil made
It is a fossil fuel. Formed from remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud. Due to high temps and pressure, remains turn into crude oil which can be drilled up and extracted
What is a finite source?
Source that will run out
What is fractional distillation used for and how does it work
. Used to seperate hydrocarbon fractions
. Crde oil is a mixture of lots of diferent hydrocarbons - mostly alkanes
. Oil heated until most of it has turned into gass. Gass enters the fractionating column
. There is a temp gradient in the column. Hot at bottom and cooler at top
. Longer hydrocarbons have higher boiling points so they condense back into liquid and drain out of bottom early on.
. Shorter hydrocarbons have lower boiling points. They condense and drain out later on near top of column
What are some of the uses of crude oil
. Feul for vehicles eg - diesel oil
. Petrochemical industry
What does cracking mean and why is it done
. Short chain hydrocarbon make good fuel but long chain hydrocarbon do not. Long chain hydrocarbon made from factional distillation is made into smaller chains through cracking process
. Cracking is a thermal decomposition reaction - breaking down molecules by heating them
What are the 2 diferent methods of cracking and how do they work
. Catalytic cracking - heat long chain of hydrocarbon to vapourise them
Vapour passes over hot powdered aluminium oxcide catalyst. Long chain splits apart on surface of the specks of catalyst
. Steam cracking - vapourise hydrocarbon, mix with steam and heat at very high temp
What are alkenes
. Hydrocarbon which contains a double bond between 2 of the carbon atoms
. The double bond means that the alkene has 2 less hydrogen atoms compared to the alkane and the same number of carbons so they are unsaturated
. The double bond can be opened up to make a single bond so carbon atoms can bond with other atoms, making them reactive
Why are alkenes reactive?
The double bond can be opened up to make a single bond so carbon atoms can bond with other atoms, making them reactive
What are the first 4 alkenes
Ethene, propene, butane, pentene
What is the general formula for alkenes
CnH²n
What is the equation for incomplete combustion
. Alkene + oxygen –> carbon monoxide + carbon dioxide + water
. Results in a yellow flame and less energy than complete
How do alkenes react
Via addition reactions. Alkenes all have functional group c=c so they all react in similar ways. Double bonds open up and leave a single bond so a new attom can join
What is it called when hydrogen react with alkene
Hydrogenation. H² is added double bond opens up
What is produced when steam reacts with alkene
Alcohol - when alkene reacts with steam, water is added across the double bond and an alcohol is formed
What do u call a halogen that has reacted with an alkene
Eg: bromine and ethene
Dibromoethane
What is the test for alkenes
Add bromine water to Saturated compound. If alkene is present, the colour of the bromine water will turn from orange to colourless
What hat are plastics made off
Long chain molecules called polymers. Polymers are long chains made up of monomers
What are addition polymers
Long chain molecules made up of unsaturated monomers. These monomer shave a double covelent bond which can open up to allow other monomers to join on to create the polymer. This is called audition polymerisation
What is the functional group of alcohol
-OH
What are the properties of aclohol
. Flammable
. Undergo complete combustion producing CO² and H²O
. Neutral PH - soluble in water
. Can react with Sodium - produce hydrogen
. Can be oxidised - react with oxygen - to form carboxylic acid
What some uses of alcohols
Used as solvents and fuels
What is fermentation and what does it produce
It is when anearobic respiration occurs in yeast cells. It produces the alcohol ethanol and also CO²
What are carboxylic acids
They are a homologous series of compounds that have the functional group -COOH.
the names of them end in ‘-anoic acid’
What do carboxylic acids react with to form salt, water and carbon dioxide
Carbonates
What is the chemical equation for esters
Alcohol + carboxylic acid –> ester + water
. Uses an acid catalyst
What does condensation polymerisation create
Polymers
What does condensation polymerisation invlove
Monomers which contain diferent functional groups
How does condensation polymerisation work
Monomers react together and bonds form between them, making polymer chains.
For each new bond that forms, a small molecule like water is lost
What is the most simplest type of condensation polymerisation
These contain only 2 diferent types of monomers, each with 2 of the same functional group
What is the number of types of monomers in addition polymerisation
Only one type containing c=c bond
How many products are formed In addition polymerisation
Only one
What is the munber of types of monomers in condensation polymerisation
2 monomer types each containing 2 of the same functional groups
Or one monomer type with 2 diferent functional groups
What do amino acids contain
An amino group and carboxylic group. Eg: glycine
What are protien made up of
Polymers of amino acids
What are DNA molecules made from
Nucleotide polymers
