Organic Chemistry Flashcards
Name the first four alkanes and their formulas.
Methane - CH4
Ethane - C2H6
Propane - C3H8
Butane - C4H10
What’s the general formula for alkanes?
CnH2n+2
The shorter the carbon chain the less v________, the more v________ and the more f____________.
viscous, volatile, flammable
What is the word equation for complete combustion?
hydrocarbon + oxygen -> carbon dioxide + water
What are the uses of alkanes?
Fuels.
What is crude oil?
A fossil fuel and a mixture.
What process is used to separate hydrocarbon fractions?
Fractional distillation.
How does fractional distillation work?
- The oil is heated until most of it has turned to gas. The gases enter a fractionating column.
- In the column there is a temperature gradient - hot at the bottom, cooler at the top.
- Longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on when near the bottom. Shorter hydrocarbons have lower boiling points so condense and drain out much later on, near the top of the column.
- The crude oil mixture is seperated into different fractions.
What is a fraction?
A mixture of hydrocarbons that contain a similar number of carbon atoms, so have similar boiling points.
What are the uses of crude oil?
Fuel for transport and the petrochemical industry.
What is cracking?
The splitting up of long-chain hyrdocarbons.
What are the two different methods of cracking?
Catalytic cracking and steam cracking.
Why is cracking needed?
Short-chain hydrocarbons are more flammable so make good fuels and are in high demand.
What are the products of cracking?
An alkane and an alkene.
What is catalytic cracking?
Once the long-chain hydrocarbons have been vapourised, the vapour is passed over hot powdered aluminium oxide (catalyst). The long-chain molecules split apart on the surface of the specks of the catalyst.
What is steam cracking?
Once the long-chain hydrocarbon has been vapourised, they are mixed with steam and then heated to a high temperature.
What is the homologous series?
A group of organic compounds that react in a similar way.
What is meant by saturated compounds?
Each carbon atom forms four single covalent bonds.
What is meant by unsaturated compounds?
They have a double carbon bond.
Are alkenes saturated or unsaturated compounds?
Unsaturated.
What is the general formula for alkenes?
CnH2n
Name the first 4 alkenes.
Ethene C2H4
Propene C3H6
Butene C4H8
Pentene C5H10
In a large supply of oxygen, how do alkenes combust?
Completely, to only produce carbon dioxide and water.
When burned in air, alkenes undergo incomplete combustion, what toxic gases is produced?
Carbon (soot) and carbon monoxide (CO).
Why is carbon monoxide dangerous?
It is poisonous and cannot be seen or smelt. Also known as the silent killer.
What is seen during incomplete combustion?
A smoky yellow flame.
Give the balanced, formula equation for the incomplete combustion of butene.
C4H8 + 5O2 -> 2CO + 2CO2 + 4H2O
What is a functional group?
A group of atoms in a molecule that determines how that molecule typically reacts.
What is the functional group of alkenes?
C=C
What is hydrogenation?
The addition of hydrogen.
What is an addition reaction?
When one molecule combines with another molecule to form a larger molecule with no other products.
How do alkenes react?
Via addition reactions.
Why are alkenes more reactive than alkanes?
The C=C double bond can open up to make a single bond allowing the two carbon atoms to bond with other atoms.
What happens when hydrogen reacts with alkenes in the presence of a catalyst?
Hydrogen can react with the double-bonded carbons to open up the double bond and form the equivalent, saturated, alkane.
What happens when alkenes react with halogens?
The molecules formed are saturated, with the C=C carbons each becoming bonded to a halogen atom.
What happens to bromine water in the presence of alkenes?
The orange bromine water turns colourless.
What is formed when steam reacts with alkenes?
Alcohols.
How is ethanol made industrially?
Ethanol can be made by mixing ethene with steam then passing over a catalyst.
After the reaction has taken place, the mixture is passed from the reactor into a condenser. Ethanol and water have a higher boiling point than ethene so both condense whilst any unreacted ethene gas is recycled back into the reactor. The alcohol can then be purified from the mixture by fractional distillation.
What is a polymer?
Lots of the same smaller molecules (monomers) joined together in one long chain to form one large molecule.
What are polymers used for?
Plastics.
What is polymerisation?
When monomers join together to form polymers.
What does polymerisation require?
High pressure and a catalyst.
What are addition polymers made from?
Unsaturated monomers.
What is addition polymerisation?
When unsaturated monomer molecules (alkenes) open up their double bonds and join together to form polymer chains.
What is the functional group of alcohols?
‘-OH’ and end in ‘-ol’
What is the general formula of an alcohol?
CnH2n+1OH
Name the first four alcohols.
Methanol CH3OH
Ethanol C2H5OH
Propanol C3H7OH
Butanol C4H9OH
What are the uses of alcohols?
Solvents and fuels.
What are the properties of the first four alcohols?
Flammable, dissolve in water to have a neutral pH, react with sodium to produce hydrogen, can be oxidised to produce a carboxylic acid.
What alcohol is found in alcoholic drinks, such as wine or beer?
Ethanol.
How is ethanol made?
Using fermentation or from ethene.
How does fermentation work?
- Fermentation uses an enzyme in yeast to covert sugars into ethanol. Carbon dioxide is also produced. This reaction occurs in a solution so the ethanol produced is aqueous.
- Fermentation happens fastest at 37°C, in a slightly acidic solution and in anaerobic conditions.
- Under these conditions, the enzyme in yeast works best to convert the sugar to alcohol. If the conditions were different, the enzyme could denature and work at a slower rate.
What is the functional group of carboxylic acids?
‘-COOH’ and ends in ‘-anoic acid’
Name the first four carboxylic acids.
Methanoic acid HCOOH
Ethanoic acid CH3COOH
Propanoic acid C2H5COOH
Butanoic acid C3H7COOH
What is the functional group of esters?
‘-COO’
Why are carboxylic acids ‘weak acids’ ?
When dissolved in water, the H+ ions don’t completely ionise.
What happens when a carboxylic acid reacts with a carbonate?
They produce a salt, water and carbon dioxide.
When a carboxylic acid is reacted with a carbonate, what is the ending of the salt produced?
‘-anoate’
How are esters formed?
When an alcohol and carboxylic acid react with an acid catalyst.
What is the ester called, produced when ethanoic acid reacts with ethanol in the presence of an acid catalyst?
Ethyl Ethanoate
What is produced when an alcohol reacts with a carboxylic acid in the presence of an acid catalyst?
Ester + water
What is condensation polymerisation?
When monomers which contain different functional groups react together and bonds form between them, making polymer chains.
During condensation polymerisation, for each new bond formed, a small molecule is lost. What is this molecule?
Water.
What are the differences between addition polymerisation and condensation polymerisation?
Addition Polymerisation
- One type of monomer containing C=C bond
- Only one product formed
- Carbon-Carbon double bond in monomer
Condensation Polymerisation
- Two types of monomer, each containing two of the same functional groups
OR
- One monomer type with two different functional groups
- Two types of product, the polymer and smaller molecule (water)
- Two reactive groups on each monomer
Name a naturally occuring Polymer.
Amino acids.
What two different functional groups does an amino acid contain?
An amino group (NH2) and a carboxyl group (COOH).
What is the smallest and simplest amino acid called?
Glycine.
What are proteins?
Polymers of amino acids.
Amino acids can form polymers known as p______________ via c_____________ p_______________.
Polypeptides, Condensation polymerisation.
What are the uses of proteins in the human body?
Enzymes work as catalysts, haemoglobin transports oxygen, antibodies form part of the immune system, majority of body tissue is made from proteins.
What are DNA molecules made from?
Nucleotide polymers.
DNA is made up of two polymer chains of monomers called n__________.
Nucleotides.
What are the smaller molecules of nucleotides known as?
A ‘base’. There are four different bases - A, C, G, T.
Simple sugars can form p____________.
Polymers.
Sugars can react through p_____________ reactions to form larger p____________.
Polymerisation, polymers.
