Organic Chemistry Flashcards
Crude oil
A mixture of different hydrocarbons
Formed from the remains of plankton that died millions of years ago and got buried in mud
Uses of crude oil
Plastic
Petrol
Pharmaceuticals
Cosmetics
Hydrocarbon
Made of hydrogen and carbon atoms
Alkane
A type of hydrocarbon
Carbon surrounded by hydrogen with single bonds
General formula for alkanes
Cn H2n+2
Why are alkanes saturated molecules?
Because carbon can only have 4 bonds
And in alkanes they are fully bonded with single molecules showing they have the maximum number of hydrogens possible
Viscosity
Thickness of a fluid
High viscosity = thick and doesn’t flow easily
Low viscosity = think and flows easily
Properties of long chain hydrocarbons
Viscos/ think (flows slowly)
Less flammable
High boiling point (requires more energy to overcome bonds)
Properties of short chain hydrocarbons
Not viscos (Thin) flows easily
Flammable
Low boiling point (not much energy required to break bonds)
How does properties of hydrocarbons change?
When written all down, they change proportionally going up or down
Eg going up they increase in viscosity
How are hydrocarbons used for fuels?
Alkanes are combusted ie burnt
What does complete combustion of alkanes release?
Carbon dioxide and water
Fractional distillation
Separating crude oil into ‘fractions’ in a column
Depending in their chain length eg long chain or shirt chain thus their properties
Done so we can use the different hydrocarbon lengths for different purposes
How does fractional distillation work?
Crude oil heated and becomes a gas
Enters the column, where it’s hot at the bottom and cool at the top
As the gas rises up the column, different hydrocarbons will reach their boiling point at different points
The long ones reach it at the hot bottom so they condense there and leave
Short ones condense into liquid at the top and leave
Very short ones remain as gases and leave
Long chain hydrocarbon uses
Fuel for ships and power stations
Bitumen/ asphalt for roads
Diesel
Short chain hydrocarbon uses
Fuel for aircraft
Petrol
Fuel for house cooking
Cracking
Process of breaking long chain hydrocarbons to be shorter
As shorter ones are more flammable and easier use for fuel
This does not involve crude oil. ONLY HYDROCARBONS
What are the products of cracking?
A short chain alkane and an alkene
Conditions for catalytic cracking
Very high temperature
Catalyst to speed it up
Steam cracking conditions
Very high temp
Steam
Alkene
Type of hydrocarbon with 1 double covalent bond between 2 carbon atoms
Alkene general formula
Cn H2n
Are alkenes saturated?
No.
Because they have 2 less hydrogen molecules than the corresponding alkane they possibly can have
Does methene exist?
No because there must be a double bond between 2 carbon atoms
But meth- only has 1 carbon atom so it’s not possible
Use of alkenes
Making polymers
As a starting material for other chemicals
More reactive than corresponding alkane
How to test for alkenes?
Add orange bromine water to it
Shake, if it’s an Alkene it goes from
Orange to colourless
NOTTTTT CLEARRRRRRR
What happens when alkenes are combusted?
They burn in air with a smoky flame
Produces carbon dioxide and water just like with alkane
Also produces unburnt carbon atoms due to incomplete combustion
Hydrogenation
Using hydrogen in order to turn an alkane into its corresponding Alkene
Conditions for hydrogenation
Temp of 150°c
A nickel catalyst
What happens in hydrogenation?
2 hydrogen atoms react with an alkene
Which 2 double bonds in the Alkene break
Thus allowing the 2 hydrogens to bond and become an alkane
Hydration
Adding water gas (steam) to an Alkene
To produce alcohol
What happens during hydration?
An Alkene reacts with a water molecule
Double bond in Alkene breaks so it’s a single carbon to carbon bond
One hydrogen bonds to the end of a carbon atom
The other hydrogen and oxygen bond to the other side
Conditions for hydration?
Temperature 300°c
Pressure 70 atm
Phosphoric acid catalyst
What is special about a hydration reaction?
It is reversible
So if we want to increase the yield pass it back through a catalyst
Alkenes reaction with halogens
When the double carbon to carbon bond breaks up
And the 2 halogen atoms bond to either side
Forming a new product
Name of product formed when halogen reacts with alkene?
Di + stem of the halogen + corresponding alkane
Eg ethene + iodine = diiodoethane
What produces alcohol using an Alkene?
Hydration of alkenes
Eg adding an extra hydrogen atom and and oxygen and hydrogen atom to the end of it
Alcohol functional group
-OH
Alcohol structural formula
CH3OH
Ethanol formula
CH3CH2OH
Why do we break the formula of alcohols up for each carbon atom?
We just do idk
Why do we use fermentation to create ethanol not hydration or ethene?
Because hydration of ethene
Requires too high temp
And lots of energy
Also because ethene is non renewable
What do we ferment to make ethanol?
Glucose
Fermentation of sugar steps
Sugar solution and yeast
Heat to 30°C
With no oxygen
Makes ethanol
Cons of fermentation
We must purify the ethanol solution after because it makes liquid ethanol
Which requires energy = not cost efficient
What happens if you add alcohol to water?
They dissolve (soluble)
And form neutral solutions
Does the solubility of alcohols change?
Yes
Long chain alcohols ie with more carbon atoms are less soluble
What happens if you react alcohol with sodium?
You make sodium _oxide (eg methoxide) and hydrogen
What happens if you react alcohol with an oxidising agent?
They make a carboxylic acid and water
What does combusting alcohol in air release?
Carbon dioxide and water
How to balance combustion equations
Start with carbon atoms
Then hydrogen atoms
Then oxygen atoms
What makes carboxylic acids?
When alcohols are reacted with an oxidising agent
Carboxylic acid functional group
C=O
|
OH
Structural formula for carboxylic acid
_COOH
How to identify what carboxylic acid it is from the structural formula?
Count the number of carbon atoms
And it’s corresponding alkane shows what acid it is
Carboxylic acid dissolved in water
They are weak acids
As they are not fully ionising
And a reversible reaction
Carboxylic acids with metal carbonates
Makes the a salt:
metal + stem of the acid + ate
For example sodium ethanoate
And carbon dioxide and water
Carboxylic acid and alcohols
Makes esters and water
Conditions for carboxylic acid + alcohol reaction
Requires sulfuric acid catalyst
Reaction for alcohol and carboxylic acid description
Hydrogen from the end of the oxygen molecule in the alcohol breaks off
The hydrogen and oxygen molecule from the carboxylic acid breaks off
These 3 form water
The rest creates the ester
Polymers
Large molecule by joining together thousands of small identical molecules (monomers)
2 different types of polymers
Addition polymers
Condensation polymers
What are addition polymers?
When ALKENE monomers make a large polymer
By opening its double bond to join them together
What are the bonds in addition polymers?
Single although the alkenes have double bonds
Short hand way of showing polymer name
Repeating unit
Repeating unit
Select 2 carbon atoms from chain
Draw atoms around it
Put in brackets with a small n outside
Repeating unit vs monomer
Repeating unit has single bond
Monomer has double bond
Repeating unit has brackets around and a small n
Otherwise same molecules used
Condensation polymer
Made from monomers
But they are not alkenes like addition polymers
And we lose small water molecules
Formation of condensation monomers
2 different monomers
These monomers have 2 of the same functional groups:
ethane diol has alcohol functional group
And hexanedioic acid with 2 carboxylic acid groups
Reacting alcohol and carboxylic acid forms ester and water so we have an ester in the middle and water at the side
Thus molecules are added and reacted at the end to form a long chain
Polyester
Thousands of monomers joined together to make the polymer
Repeating unit for condensation polymers
Work out what the 2 functional groups will form
Select 2 of these
Draw it with brackets around it with the number at the side of it small outside the bracket
