Organic Chemistry Flashcards by Livia Buxton

Crude oil

A mixture of different hydrocarbons
Formed from the remains of plankton that died millions of years ago and got buried in mud

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Uses of crude oil

Plastic
Petrol
Pharmaceuticals
Cosmetics

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Hydrocarbon

Made of hydrogen and carbon atoms

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Alkane

A type of hydrocarbon
Carbon surrounded by hydrogen with single bonds

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General formula for alkanes

Cn H2n+2

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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

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Viscosity

Thickness of a fluid
High viscosity = thick and doesn’t flow easily
Low viscosity = think and flows easily

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Properties of long chain hydrocarbons

Viscos/ think (flows slowly)
Less flammable
High boiling point (requires more energy to overcome bonds)

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Properties of short chain hydrocarbons

Not viscos (Thin) flows easily
Flammable
Low boiling point (not much energy required to break bonds)

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How does properties of hydrocarbons change?

When written all down, they change proportionally going up or down
Eg going up they increase in viscosity

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How are hydrocarbons used for fuels?

Alkanes are combusted ie burnt

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What does complete combustion of alkanes release?

Carbon dioxide and water

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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

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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

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Long chain hydrocarbon uses

Fuel for ships and power stations
Bitumen/ asphalt for roads
Diesel

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Short chain hydrocarbon uses

Fuel for aircraft
Petrol
Fuel for house cooking

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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

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What are the products of cracking?

A short chain alkane and an alkene

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Conditions for catalytic cracking

Very high temperature
Catalyst to speed it up

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Steam cracking conditions

Very high temp
Steam

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Alkene

Type of hydrocarbon with 1 double covalent bond between 2 carbon atoms

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Alkene general formula

Cn H2n

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Are alkenes saturated?

No.
Because they have 2 less hydrogen molecules than the corresponding alkane they possibly can have

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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

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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

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