Organic chemistry Flashcards
What is a hydrocarbon?
A covalently bonded alkane consisting of hydrogen and carbon
What is the hydrocarbon general formula?
CnH2n+2
What is the homologous series?
Alkanes are a homologous series of hydrocarbons
This means
- the molecular formulae of neighbouring members differ by CH2
- that they show a gradual variation in physical properties such as boiling points
- that they have similar chemical properties
What is crude oil?
A mixture of different length hydrocarbons
What are the properties of small length hydrocarbons?
Boiling point: Low Flammability: High Cleanliness of flame: clean Viscosity: thin Number of atoms: low
What are the properties of long hydrocarbons?
Boiling point: High Flammability: Low Cleanliness of flame: low Viscosity: thick Number of atoms: high
What is a feedstock?
A chemical that can be produced in fractional distillation which can be use to make other chemicals such as:
- solvents
- lubricants
- detergents
- polymers
What are the two types of cracking?
Catalytic cracking which uses heat and a catalyst
or
steam cracking where we use heat and steam
What is an alkene?
It is a hydrocarbon with a double carbon=carbon bond.
What is the difference between alkenes and their alkanes?
- Alkenes have at least one double carbon=carbon bond.
- Alkenes are more reactive than their alkane
- Alkenes are unsaturated because they have two less hydrogen atoms than their equivalent alkane
How do we test for alkenes?
We use bromine water (yellow) and add the solution. If it turns colourless then there is an alkene present
Yellow->colourless
What is the general formula for alkenes?
CnH2n
Why do alkenes produce unburnt carbon atoms when combusted?
Because they undergo incomplete combustion
What is the difference between complete and incomplete combustion?
During incomplete combustion, hydrogen is still oxidised to water vapour but:
- carbon may only be partially oxidised to carbon monoxide
- carbon particles will be given out
- less energy is given out
What is the alkene functional group?
The carbon double bond
What is hydrogenation?
When an alkene is reacted at 150’c with a nickel catalyst to produce and alkane.
The double carbon bond splits to allow the two hydrogen atoms in
What are alcohols?
a family of organic carbon based compounds that are part of the homologous series
What is the functional group of alcohols?
the -OH group
What are the common uses of alcohols?
- Fuels
- solvents
- Alcoholic drinks
What are the structures of the first three alcohols?
Methanol: CH3 OH
ethanol: CH3 CH2 OH
Propanol: CH3 CH2 CH2 Oh
What are the advantages and disadvantages of using hydration to make ethanol from ethene?
+ Produces a high yield
- requires a high temperature
- non renewable crude oil
What are the advantages and disadvantages of producing ethanol through fermentation?
+ Uses yeast and a sugar solution which is renewable as can be grown
+doesn’t require much energy, 30’c
- the ethanol requires to be separated through distillation as it is made as part of a solution
-reaction must take lace without oxygen
glucose -> ethanol + CO2
(yeast)
What happens when a alcohol reacts with a
a carboxylic acid and water
What are the first three carboxylic acids structural formula
Methanoic acid
HCOOH
Ethanoic acid
CH3COOH
Propanoic acid
CH3CH2COOH
What are carboxylic acids weak when in solution?
Because they only partially ionise the aqueous solution
What are polymers?
a long chain of monomers
How does addition polymerisation work?
Alkene monomers split their double carbon bond to join together to make a long polymer chain
How do we write the repeating unit of a polymer?
take on of the sections and put brackets round it with a small n in the bottom right corner
What is condensation polymerisation?
When two or more different monomers join to form a long chain
