Organic chemistry

Crude oil:

• How did Crude oil form:

  • It formed due to the effect of extremely high pressures and temperatures on the remains of biomass, of mainly plankton that were buried in deep seas under many layers mud

• What is crude oil made from:

  • Crude oil is a finite resource that is mainly made of hydrocarbons and also naturally

Hydrocarbons:

Alkanes:

• What are alkanes and general formula

  • A group of saturated hydrocarbon meaning there are carbon to carbon double bonds

  • Its general formula is CnH2n+2

• What reactions can alkanes have:

  • Alkanes are generally unreactive compounds

  • They can undergo combustion reactions

  • They can be cracked into alkenes and alkanes which are smaller chain lengths and therefore are more useful

  • They can also react with halogens in the presence of light

• What are the first 4 alkanes are :

  • Methane(CH4), Ethane(C2H6), Propane(C3H8), Butane(C4H10)

Fractional distillation:

• Why is crude oil separated:

  • Crude oil alone is not a very useful mixture, but the different hydrocarbons that make up the crude oil, called fractions, have much more value

• What properties do each fraction have:

  • Each fraction consists of groups of hydrocarbons with similar chain lengths

  • The molecules in each fraction have the same properties and boiling points which depends on the chain length

• What is the process of fractional distilation:

  • Vapourised crude oil enters the fractionating column, which has a concentration gradient, which the hottest part being at the bottom and the coldest part being at the top.

  • Fractions then divide based on boiling points, with hydrocarbons with the longest chain lengths condensing at the bottom and hydrocarbons with the shortest chain lengths condense at the top

What are the uses of petrochemicals(fractions):

• Liquified petroleum gas - domestic heating and cooking

• Petrol - Fuel for cars (gasoline)

• Kerosene - Jet fuel (paraffin)

• Diesel - Diesel engines (gas oil)

• Heavy fuel oil - Ships and power stations

• Bitumen - Surfacing roads and roofs

Properties of hydrocarbons:

• How does Volatility change and why:(How quickly an object reaches its boiling point)

  • The larger the size of hydrocarbon the higher the boiling point:

    • That is because as the molecules get larger, the intermolecular forces of attraction between molecules becomes greater as there are more electrons in the molecules and greater surface area contact between them and so they require more energy to break

• How does Viscosity change and why:

  • It refers to the ease of flow of a liquid - If a liquid is viscous, it is thick and not runny

  • The viscosity also increases as the chain length increases.

    • This is also due to the intermolecular forces of attraction as molecular size increases. An increased viscosity means that longer chain alkanes are useful as lubricants in machinery as they are less likely to burn and function to reduce friction between moving parts

• How does Flammability change and why:

  • The flammability of a hydrocarbon decreases as the chain length increases

    • This makes them very useful as fuels, releasing large amounts of energy while using a lower quantity

Alkenes:

• What is an alkene and its general formula:

  • Unsaturated hydrocarbon with a carbon to carbon double bond and that it is its functional group C=C

  • It has the general formula of CnH2n

• Why are alkenes more reactive than alkanes:

  • and are much more reactive than alkanes as the double bonds are able to open up and take up other atoms, which makes them more useful than alkanes

• What are The first 4 alkenes are:

  • ethene, propene, butene, pentene

Cracking(thermal decomposition process):

• What is meant by cracking:

  • Cracking is the breaking down of long chain hydrocarbons into shorter chain, more useful, hydrocarbons, and some of them being unsaturated (using heat)

• What are the 2 main methods of cracking:

  • Steam cracking

  • Catalytic cracking

• What are the conditions of Steam cracking:

  • Vapourised long chain hydrocarbons

  • Mixed with steam

  • 800C

  • Under pressure

• What are the conditions of Catalytic cracking:

  • Long chain hydrocarbon is turned into gas

  • Passed over powdered aluminium oxide catalyst

  • Temperature of 550C

• What are the 2 Main reasons for cracking:

  • To meet the high demand of shorter chain alkenes and alkanes as they are more useful

  • It produces alkenes which are very useful as feedstock(A raw material used to provide reactants in an industrial reaction) in the petrochemical industry

Addition reacts with alkenes:

1. Describe the process of Halogenation

   • A halogen can be added to alkenes. When a halogen reacts with an alkene, the double bond opens up to allow for the halogen to take place. This then forms a saturated molecule

   • What are the Conditions:

     • No catalyst

     • room temperature

     • room pressure

2. Describe the process of Hydration:

   • Steam can be added to alkenes. When steam reacts with an alkene, the double bonds open up, to take a hydrogen atom and an hydroxide molecule, which have been separated from their original form as a water molecule when the reaction occurs

   • This then forms an alcohol. Main example is ethanol, which is formed from ethene and steam, which is an industrial way to make ethanol

   • What are the Conditions for this reaction:

     • Phosphoric acid catalyst

     • 300C

     • 60 atmospheres pressure

3. Describe the process hydrogenation:

   • Hydrogen can be added to alkenes. When hydrogen reacts with an alkene, the double bons opens and allows for hydrogen to take place, this forms a saturated alkane

   • What are the Conditions for ethene reaction:

     • Nickel catalyst

     • 150C

Bromination of ethene:

• What type of reaction is bromination:

  • This is a form of halogenation, where bromine is added to ethene, which forms dibromoethane

• Describe the bromine water test:

  • Bromine water is added to a test tube which is orange

  • It is orange because bromine is orange and is in the solution

  • when an alkene reacts with the bromine water, it goes from orange to colourless, however when it reacts with an alkane stays orange.

  • It does this because if it is an alkene then it will react with the bromine in the water, and the bromine will no longer be free to leave the orange colour in solution

Alcohols:

• What is their functional group and general formula:

  • Hydroxyl group

  • CnH2n+1OH

• What are the first 4 Alcohols:

  • Methanol

  • Ethanol

  • Propanol

  • Butanol

• What are the properties of alcohols:

  • Colourless liquids

  • Dissolve in water to form neutral solutions

  • Very flammable

  • Can be oxidised without combustions

• What are the 4 main reactions with alcohols:

  • Combustions

  • React with metals such as sodium

  • Dissolve in water

  • Oxidising of alcohols

• What happens when ethanol reacts with sodium:

  • Bubbles of hydrogen gas

  • Produces a colourless solution(sodium ethoxide)

• What happens when you try to dissolve an alcohol in water:

  • It easily dissolves if it is the first 4 alcohols due to them having a short chain length to produce a neutral solution

  • However, the solubility decreases as the chain length increases

• What happens when alcohols are oxidises:

  • They can be oxidised using an oxidising agent to produce a carboxylic acid

Fermentation to create ethanol:

• What are the uses of ethanol:

  • Alcoholic drinks

  • Fuel

  • Solvent

• What is the process of fermentation:

  • Sugar or starch is dissolved in water and yeast is added

  • To produce Ethanol and CO2

• What are the conditions for fermentation:

  • Warm temperature of 25C to 35C

  • An air lock to allow carbon dioxide out, while stopping air getting in

• Why is yeast:

  • Because it is a fungus that contains enzymes which break down glucose

Carboxylic acids:

• What is the functional group and general formula:

  • Carboxyl group -COOH

  • CnH2n+1COOH

• What happens when they react with Carbonates:

  • They produce a salt, water and CO2

• What happens when they react with water:

  • They dissolve to form acidic solutions with a pH values less than 7 but over 3 because they partially ionise in water due to them being acids

• What happens when they react with alcohols:

  • They form an ester and water, the main one is methyl ethanoate

Condensation polymerisation:

• What is condensation polymerisation:

  • When 2 monomers are linked together with the removal of a small molecule, usually water

• How is a polyester formed:

  • A reaction between a diol and dicarboxylic acid to form a polyester and water

Naturally occurring polymers:

Proteins:

• What are Amino Acids:

  • They are Acids containing NH2(amino group) and a carboxylic acid group(COOH)

• How many amino acids are there:

  • 20

• How are polypeptides formed:

  • They are condensation polymers formed from amino acids monomers joined together by an amide link

• What is the functional group of proteins:

  • CONH

• What is the simplest protein:

  • Glycine

DNA:

• How are nucleotides held together:

  • They are held by hydrogen bonds between bases

Starch and cellulose:

• What are carbohydrates compounds of:

  • Carbon

  • Hydrogen

  • Oxygen

• What are the 2 types of carbohydrates and what are their names:

  • Simple carbohydrates - monosaccharides(sugars: fructose, glucose)

  • Complex carbohydrates - polysaccharides(starches and cellulose)

• What are the monomers for starch:

  • The monomers for starch are simple sugars and are made from the same monomers

• What type of polymerisation forms starch and cellulose:

  • Condensation