Organic Chemistry Flashcards
What two structures can carbon form?
- giant macromolecular structures
- simple molecular structures
What are the natural polymers?
- DNA/RNA
- proteins
- lipids
- carbohydrates
What is crude oil?
A mixture of hydrocarbons
What is a homologous series?
A family of organic compounds with:
- similar chemical properties
- the same general formula
- the same functional group
Give the names of the two homologous series for GCSE:
alkanes
alkenes
What is the life form which forms crude oil?
Aquatic life (ancient biomass)
What is a hydrocarbon?
A compound containing only carbon and hydrogen
What is the functional group for Alkanes?
Single bonded carbons
Saturated
What is the general formula for Alkanes?
C n H 2 n+2
What are the first four members of the alkane group?
methane, ethane, propane, butane
What is the functional group for alkenes?
Double carbon bond
Unsaturated
What is the general formula for alkenes?
C n H 2n
What are the first four members of the alkene group?
Ethene, propene, butene, pentene
What are fractions?
The different groups of hydrocarbons separated during fractional distillation
What are the different fractions?
natural gases (methane, ethane, propane, butane)
liquids (petrol, diesel, kerosene, fuel oil)
solid (wax, butamen)
What is kerosene used in?
aeroplane fuel
What is the structure of a hydrocarbon?
Simple molecular structures
What is the bonding in a hydrocarbon?
Covalent bonds between atoms but weak intermolecular forces between molecules
What is the relationship between the size of the hydrocarbon chain and the boiling point? Why?
As the length of the hydrocarbon chain increases. so does the boiling point. This is since the IMFs increases as there are more electrons.
What is the relationship between the size of the hydrocarbon chain and the flammability?
As the length of the hydrocarbon chain increases, the flammabiity decreases.
What is flammability?
The ability to burst into flames
What is the relationship between the size of the hydrocarbon chain and the viscosity?
As the length of the hydrocarbon chain increases, the greater the viscosity.
What must be done to crude oil for it to be of any use?
Processed or refined in an oil refinery
Describe how fractional distillation works:
1) Crude oil is boiled to 450 degrees and pumped into the bottom of a fractionating column, where it vaporises
2) The column is very hot at the bottom but much cooler at the top (temperature gradient). As the vaporised oil rises, it cools and condenses.
3) Heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column
4) Lighter fractions have a lower boiling point and condense further up the column
What is naptha used for?
As a chemical feedstock and diluting diesel
What type of reaction is the combustion of alkanes?
Oxidation as the addition of oxygen occurs
What is cracking?
The decomposition of long chain alkanes to make more useful shorter chain alkanes and an alkene
Why is cracking conducted?
- high demand for short chainlength hydrocarbons which are used as fuels
- demand for alkenes, needed to make polymers
- crude oil contains lots of long chainlength alkanes which aren’t useful
What are the two types of cracking?
- catalytic cracking
- steam cracking
What is catalytic cracking?
Hydrocarbon vapours passed over a hot powedered catalyst e.g. Aluminium Oxide at 450 degrees
What is steam cracking?
Mixing long chainlength hydrocarbons with steam and heating to a very high temperature
What is the general fromula for a cracking reaction?
Long Chain hydrocarbon = short chain alkane + alkene
What is the test for unsaturation (alkene)?
Add orange bromine water to alkene smaple and the orange solution will turn colourless if an alkene is present
What is the relative reactivity of a saturated and unsaturated molecule?
Unsaturated is more reactive than saturated
What is viscosity a measure of?
The ability for molecules to slid past each other
What is isomerism?
When atoms can be arranged differently to make different compounds with different properties
What does an alkene react differently to an alkane?
It contains a double carbon bond
What is the equation for the reaction between bromine water and an alkene?
Bromine + Alkene = 1,2 - dibromo(prefix)ane
What is the equation for the reaction between bromine water and ethene?
Ethene + Bromine = 1,2 - dibromoethane
What type of reaction is the reaction between bromine and an alkene?
Addition reaction
What happens when hydrogen is added to an alkene?
The double carbon bons saturates, turning the alkene into an alkane
What happens when steam is added to an alkene?
An alcohol is formed
What is a chemical feedstock? Give an example from crude oil
A starting chemical which can be used to produce many other products e.g. naptha
What are the products of complete combustion between an alkene and oxygen?
Carbon dioxide and water
What are the products of incomplete combustion between an alkene and oxygen?
Carbon monoxide and water
Why are the flames typically smoky in a reaction between an alkene and oxygen?
The alkene is incompletely combusting
Describe the conditions of a hydrogenation reaction?
nickel catalyst at 150 degrees
Describe the conditions of a hydration reacction:
High pressure, high temperature (300) and with a catalyst of phosphoric acid
What is the commercial use of an alkene reacted with hydrogen?
Used to harden margerine
What is the commerical use of producing alcohols from alkene hydration?
Solvent, disinfectant and perfumes
What is the order of atoms displayed in the formula?
C, H, O, N, P, S and then the rest
What are the conditions for a reaction between a halogen and alkene?
Room temperature and pressure
What is the commerical use a reaction between bromine and alkene?
To test for unsaturation
What is the product when a halogen and alkene react?
Halogenoalkane
Describe the bond process in a reaction between a halogen and an alkene:
The carbon double bond breaks and the bromine molecule breaks. The bromine atoms then add to each carbon.
What happens to the functional group of an alkene in an addition reaction?
the double bond splits and adds on to the reactant
Name the first four alcohols?
Methanol,ethanol, propanol, butanol
What is the functional group for an alcohol?
O-H
What is the relationship between alcohol chainlengeth and reaction with sodium? Why?
The more carbons in the alcohol, the less vigirous the reaction is. Increasing the chainlength decreases solubility
Describe the observations in a reaction between sodium and alcohols?
- gas is produced
- sodium moves about on surface (gas gives upthrust)
- sodium dissolves
Why can the hydrogen produced in a reaction between an alcohol and sodium not be tested with the squeaky pop?
The alcohol is highly flammable so don’t want naked flame near it
What coloured flame indicates complete combustion of alcohol?
Blue
What coloured flame indicates incomplete combustion of alcohol?
Yellow
What is the relationship between alcohol chain length and combustion?
as carbon chainlength increases, less complete combustion occurs and incomplete combustion increases with alcohols
What happens in a reaction between low carbon chain alcohols and water?
The low carbon chain alcohols will dissolve in water to form a solution
What happens between water and alcohols as the chainlength increases?
More layers build up on top of the water than dissolve in it, making the solution unclear
Why does not all the alcohol dissolve in water?
- the functional group is hydrophillic
- the rest is hydrophobic
What does hydrophillic mean?
- miscible - will dissolve in water to make a clear solution
What does hydrophobic mean?
- immiscible - will not dissolve in water and will instead build up on top of it
What is the pH of a solution with a dissolved alcohol in water?
Neutral 7
What are the two ways to produce alcohol?
- hydration
- fermentation
What are the reagents in fermentation?
Sugar dissolved in water
What are the conditions of fermentation?
Yeast enzymes at 37 degrees without oxygen, in slightly acidic conditions
Is hydration sustainable? Why?
No as the ethene comes from a crude oil source fractionally distilllated and cracked
Is fermentation sustainable? WHy?
Yes as it uses a renewable resource
What type of process is fermentation?
Batch process
What type of process is hydration?
continuous process
What is the use of ethanol made from fermentation?
Alcoholic drinks and biofuel
How can the use of bioethanol be deemed as carbon neutral?
- if the equation for photosynthesis, fermentation and ethanol combustion are written out, these are the three reactions which ethanol undergoes
- all the reactants can be cancelled out with the products
- meaning no more carbon is contributed into the atmosphere
How are carboxylic acids made?
By oxidising an alcohol with an agent such as potassium dichromate in sulfuric acid
How do we know when the alcohol has been oxidised?
The potassium dichromate is a bright orange colour which will turn green when reduced
How can we tell if a solution is acidic?
- add universal indicator and will turn red/orange/yellow
- dip in blue litmus paper and it will turn red
What type of acids are weak?
Organic acids e.g. carboxylic acids
What is the functional group of a carboxylic acid?
COOH
What is the salt functional group formed from a carboxylic acid?
COO-
How is the acid carboxylic acid named?
-talking the name of the alkane, removing the -e and adding -oic acid
How is the salt from carboxylic acid named?
- taking the name of the alkane, remove the -e and adding -oate
What are the first four carboxylic acids?
Methanoic acid
Ethanoic acid
Propanoic acid
Butanoic acid
What are the first four carboxylic salts?
methanoate
ethanoate
propanoate
butanoate
What is formed when a carboxylic acid and a metal carbonate react?
a metal salt, carbon dioxide and water
What is the charge of a carbonate ion?
2-
What type of reactions are Ester and polyester formations?
Condensation
What is a condensation reaction?
A reaction which releases a molecule of water
What is the reaction for Ester formation?
Alcohol + Carboxylic acid = Ester + water
What are the conditions for the Ester reaction?
the carboxylic acid is hot
Write out the equation for the reaction of ethanol and ethanoic acid
Ethanol + ethanoic acid = Ethyl ethanoate + water
What is the Ester formed from methanol and ethanoic acid ?
Methyl ethanoate
What is the Ester formed from propanol and methanoic acid?
Propyl methanoate
What is removed from the alcohol and carboxylic acid in a formation reaction to make the water?
The hydrogen atom from the O-H in the alcohol and the H-O from the carboxylic acid
What is an Ester linkage ?
A carbon atom with a single covalent bond to an oxygen atom and a double covalent bond to another oxygen atom
What are the two reactants to make a polyester ?
Dialcohol and dicarboxylic Acid
Why do the reactants in polyester formation have to be di— ?
So the functional groups are at either end of the molecule to continually link the different molecules producing a chain
What are removed from the alcohol and acid in polymer formation?
The H from the alcohol and the OH from the acid
What are the ends of the polyester with no element attached to the bond called?
Trailing bonds
How many water molecules are released in a polyester reaction?
Double the amount of dialcohol and dicarboxylic acid molecules there are
What is a polymer?
A large compound which replicates a repeating unit many times. It has a simple molecular structure
What is an amide linkage?
A single bonded carbon and nitrogen atom with a double bond oxygen on the carbon and a single bond hydrogen on the nitrogen
What polymer is made when it contains an amide linkage functional group?
A polyamide
What are the natural polyesters?
fats/lipids
What type of compound is a polyester?
Synthetic
What are polyamides made from?
A dicarboxylic acid and a diamine monomer
What are the synthetic polyamides?
Nylon and kevlar
What are the natural polyamides?
Dipeptides and proteins
What are removed from the molecules in polyamide formation to make the water molecules?
The OH from the acid and one of the H’s from the amine
What is a diamine molecule?
H2N - (C) - NH2
How many amino acids are there?
20
What is the structure of an amino acid?
An amine part linked to carbon bonded with a hydrogen and (R) which is linked to the acid functional group (COOH)
What changes in the amino acid structure to make the different types?
The (R) bonded below the carbon atom
What do two monomores of amino acids make?
A dipeptide and a water molecule
What is a polypeptide formed from?
Many dipeptides joined with other amino acids
What does a protein consist of?
4 polypeptides
What is removed from the amino acids in condensation polymerisation?
The OH from the COOH and an H from the NH2
What is the monomer of DNA?
A nucleotide
What are the four nucleotides?
Thymine, adenine and guanine, cytosine
How do nucleotides combine?
In a condensation polymerisation
What is the structure of DNA?
Two long polymer chains of 4 types of nucleotides, held together in a double helix
What does deoxyribonucleic acid do?
Store genetic information
How many types of monomers are need for a condensation polymerisation and an addition polymerisation?
2 for condensation and 1 for addition
How many products are there in addition polymerisation? Condensation?
2 in condensation and 1 in addition
What is the linkage in an addition polymerisation?
A carbon atom singly bonded to another carbon atom
What is the functional group for an addition polymerisation?
Alkenes (carbon double bond carbon)
Is the product of addition polymerisation biodegradable?
No as it is a plastic
Is the product of condensation polymerisation biodegradable?
yes
What are the uses of substances produced by the petrochemical industry?
fuel, solvent, lubricant, polymer, detergent
What are the features of steam cracking?
- high temperature
- quick
- lots of alkenes made
What molecules does catalytic cracking typically make?
More small chain alkanes
What can be changed in order to change the properties of a polymer?
- change the monomers from which the polymer is made
- change the conditions (temp, pressure, catalyst) used in the reaction
Describe how catalytic cracking works:
- large alkane is heated until it vaporises
- it is passed over a hot catalyst (zeolite)
- which cracks the large alkane into small alkanes
Why is methanoic acid weak?
Since it only partially ionises in an aqeuous solution meaning there is a low concentration of H+ ions
What are the typical conditions for polymerisation?
High pressure and a catalyst
In what type of flame do alkenes combust?
A smoky yellow flame
Why are alcohols better solvents than water?
It can dissolve in hydrocarbons, oils and fats whereas water can’t
How do the nucleotides stay together in DNA?
Via cross links
What catalyst is used in ester production?
An acid catalyst
