This page contains the detailed and easy notes for AQA GCSE Chemistry Organic Chemistry for revision and understanding Organic Chemistry.

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 GCSE OCR Chemistry Complete Revision Summary

ORGANIC CHEMISTRY

Organic Chemistry

• Hydrocarbons and Crude Oil
• Alkanes
• Fractional Distillation
• Properties of Hydrocarbons
• Cracking
• Alkenes
• Reaction of Alkenes
• Alcohols
• Carboxylic Acid
• Addition Polymerization
• Condensation Polymerization
• Amino Acids
• DNA

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CRUDE OIL

• It is a black thick liquid which takes millions of years to form.
• It is the mixture of hydrocarbon.
• Hydrocarbon are the compounds made up of carbon and hydrogen only.
• The components of the crude oil are important and the crude oil is separated by the process of fractional distillation.

HYDROCARBON PROPERTIES

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FRACTIONAL DISTILLATION OF CRUDE OIL

• Separating the mixtures on the basis of boiling points.
• It is separated in fractionating column with different substances of similar boiling points

L – Look

G – Great

K – Kid

D – Doing

R – Roll

 CRACKING –Thermal decomposition of longer chain hydrocarbon into a shorter chain alkane and alkenes

Thermal Cracking                                               Catalytic Cracking

It is done at a very high temperature                     It is done using a catalyst

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ORGANIC CHEMISTRY (2)

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WHY CRACKING

• Shorter chain alkanes are more in demand as they are more efficient fuel which fractional distillation alone cannot meet.
• Alkenes are required for polymerization and synthesize other hydrocarbons which fractional distillation cannot meet.

ALKANES – Saturated Hydrocarbon

Carbon-carbon single bond                    made up of carbon and hydrogen

General Formulae  C_nH_2n+2

Methane – CH₄

Ethane – C₂H₆

Propane – C₃H₈

Butane – C₄H₁₀

Pentane – C₅H₁₂

Homologous Series – Members of the same family have similar functional group similar chemical properties and general formulae but different physical property and each members differs from successive by CH₂.

COMBUSTION

PRODUCTS OF COMBUSTION

Carbon Dioxide Test   

    Limewater Test     Carbon Dioxide will turn limewater milky

    Water Test

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FUNCTIONAL GROUPS
Groups of atoms that give special properties and reactions to the organic molecule

	Functional Groups	Examples	Formation
ALKENES	=	Ethene, propene, butene, pentene	Cracking of crude oil
ALCOHOLS	-OH	methanol, ethanol, propanol, butanol, pentanol	Reaction of alkene with water
CARBOXYLIC ACID		methanoic acid, ethanoic acid, propanoic acid, butanoic acid.	Oxidation of alcohols
ESTERS		methyl ethanoate, ethyl ethanoate	Reaction of alcohols and carboxylic acid

ALKENES

Unsaturated Hydrocarbon

• Compounds which have carbon-carbon double bond
• Compounds made up of carbon and hydrogen only

GENERAL FORMAULE  C_nH_2n

Useful to make polymers, alkanes, alcohols

MANUFACTURE OF ETHANOL

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REACTIONS OF ALKENES

ALCOHOLS – Have functional Group –OH

General Formulae

C_nH2_n+1 OH

Formed by replacing hydrogen of alkane with OH group

Used as fuel, solvents, spirits

REACTIONS OF ALCOHOLS

COMBUSTION

• It can undergo complete or incomplete combustion. Complete combustion produces carbon dioxide and water.
• Ethanol + Oxygen = Carbon dioxide + water

C₂H₅OH + O₂                                 CO₂ + H₂O

•  Incomplete combustion produces carbon dioxide and water.
• Ethanol + Oxygen = Carbon monoxide + water

 C₂H₅OH + O₂                                 CO + H₂O

OXIDATION

• Alcohols are oxidised to carboxylic acid in the presence of oxidising agent.
• Methanol   Methanoic Acid
• Ethanol    Ethanoic Acid
• Oxidising agent used is acidified potassium dichromate solution

METAL

Alcohols react with metals to form salt and hydrogen.

2C₂H₅OH + 2Ca                                 2C₂H₅OCa + H₂

CARBOXYLIC ACID

Weak Acids

Carboxylic Acids are weak acids as they are partially dissociated in water to release H+ ions.

CH₃COOH ⇌    CH₃COO^– + H⁺

Metal oxides and Metal hydroxide

Carboxylic Acid reacts with metal oxides and metal hydroxide to form salt and water.

CH₃COOH + NaOH                                 CH₃COONa + H₂O

Metal carbonate

Carboxylic Acid reacts with metal carbonate to form salt, water and carbon dioxide.

CH₃COOH + Li₂CO₃                                 CH₃COOLi + CO₂ + H₂O

                        
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ESTERS

• Fruity smelling compounds
• Used in the manufacture of perfumes, foods and cosmetics.

CARBOXYLIC ACID + ALCOHOLS               ESTERS + WATER

Alkyl alkanoate

Methanoic Acid + Methanol                           Methyl methanoate + Water

ADDITION POLYMERIZATION

• The individuals unit that polymerizes to form a polymers is known as a monomers. Eg Ethene
• The structure formed by the polymerization of the monomer is a polymers.

Polymers are materials made by linking up smaller repeating chemical units.

Some bend and stretch – rubber and polyester.

Some hard and tough – epoxies and glass.

ADDITION POLYMERS

1. a) Formed by addition reaction.
2. b) Require only one monomer generally an alkene
3. c) Nothing is lost in the reaction.

eg Polyethene, polypropene

CONDENSATION POLYMERS

1. a) Requires two monomers
2. b) Requires two functional group
3. c) Formed by condensation reaction.
4. d) A small molecule of water is
5. e) Example: Nylon a polyester

NATURAL POLYMERS

1. a) They are found naturally
2. b) All the complex biomolecules are polymers

 DNA

1. a) DNA is polynucleotide
2. b) Nucleotide = Phosphate + Sugar + Nitrogenous Bases
3. c) There are four bases present in the DNA

• Adenine
• Thymine
• Guanine
• Cytosine

KEY TERMS

Hydrocarbon – Hydrocarbon are the compounds made up of carbon and hydrogen only.

Crude Oil – It is a black thick liquid which takes millions of years to form. It is the mixture of hydrocarbon.

Fractional Distillation – Separating the mixtures on the basis of boiling points.

Alkanes – Saturated Hydrocarbon. Carbon-carbon single bond. Made up of carbon and hydrogen only

Saturated hydrocarbon – Saturated Hydrocarbons have only carbon-carbon single bonds.

Unsaturated hydrocarbon – Unsaturated Hydrocarbons have carbon-carbon double bonds and triple bonds.

General Formula – It applies to families of compounds; provides a way to predict the molecular formula of the molecule, based on the number of carbon atoms it contains.

Viscosity – movement of flow. A fluid with low viscosity flows easily

Flammable – Flammable materials are combustible materials that can easily ignite at room temperature

Complete Combustion – Fuel is completely burned. Produces Carbon dioxide and water.

Incomplete Combustion – Fuel is partially burned due to limited supply of oxygen. Produces Carbon Monoxide and Water.

Cracking – Thermal decomposition of longer chain hydrocarbon into a shorter chain alkane and alkenes

Alkenes – Unsaturated Hydrocarbon. Compounds which have carbon-carbon double bond. Compounds made up of carbon and hydrogen only

Functional Group – Groups of atoms that give special properties and reactions to the organic molecule

Homologous Series – Members of the same family have similar functional group similar chemical properties and general formulae but different physical property and each members differs from successive by CH₂

Alcohols – Have functional Group –OH. The General Formulae of Alcohols is CnH_2n+1 OH. Used as fuel, solvents, spirits

Carboxylic Acid – Carboxylic Acids are weak acids as they are partially dissociated in water to release H+ ions.

Esters – Fruity smelling compounds. Used in the manufacture of perfumes, foods and cosmetics.

Fermentation – Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes.

Weak Acid – Weak acids are only partially ionized in their solutions.

Monomers – The individuals unit that polymerizes to form a polymers is known as a monomers. Eg Ethene

Polymers – The structure formed by the polymerization of the monomer is a polymers. Polymers are materials made by linking up smaller repeating chemical units.

Some bend and stretch – rubber and polyester.

Some hard and tough – epoxies and glass.

Addition Polymerization – It is the process of repeated addition of monomers with double or triple bonds to form polymers. There is no loss of an atom or a molecule. Ex – PVC, polyethene, Teflon.

Condensation Polymerization – It is a process that involves repeated condensation reactions between two different monomers. There is a loss of a molecule of water, ammonia etc as a by-product. Ex – Nylon, bakelite, silicon.

Monosaccharide – Simplest carbohydrates (single units). They cannot be hydrolyzed into smaller units. Ex – Glucose, fructose.

Polysaccharide – Formed of numerous monosaccharide units. Ex – starch, cellulose

Starch – It is the reserve food material of plant cells. It consists of two components- amylose and amylopectin, both glucose polymers.

Cellulose – Main structural polysaccharide of plants. It is a long, unbranched chain of about 6,000 glucose units with molecular weight between 0.5 to 2.5 million.

Proteins – The proteins are linear unbranched polymers of Amino acids. The proteins are composed of carbon, hydrogen, oxygen, nitrogen, and Sulphur.

DNA – It is a long, double chain of deoxyribonucleotide units. DNA is the genetic material and forms molecular basis of heredity in all organisms.

Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons

Image Source:

Wikipedia

Wikimedia

Commons

Flickr

Pixabay

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

Hydrocarbon

• Carbon Compounds as Fuels & Feedstock 1 MS
• Carbon Compounds as Fuels & Feedstock 1 QP
• Carbon Compounds as Fuels & Feedstock 2 MS
• Carbon Compounds as Fuels & Feedstock 2 QP
• Carbon Compounds as Fuels & Feedstock 3 MS
• Carbon Compounds as Fuels & Feedstock 3 QP

Reaction Of Alkenes

• Reactions of Alkenes and Alcohols 1 MS
• Reactions of Alkenes and Alcohols 1 QP
• Reactions of Alkenes and Alcohols 2 MS
• Reactions of Alkenes and Alcohols 2 QP
• Reactions of Alkenes and Alcohols 3 MS
• Reactions of Alkenes and Alcohols 3 QP

Polymers

• Synthetic & Naturally Occurring Polymers 1 MS
• Synthetic & Naturally Occurring Polymers 1 QP
• Synthetic & Naturally Occurring Polymers 2 MS
• Synthetic & Naturally Occurring Polymers 2 QP
• Synthetic & Naturally Occurring Polymers 3 MS
• Synthetic & Naturally Occurring Polymers 3 QP.