Organic Chemistry (7) Flashcards
What is crude oil?
Crude oil is a mixture of compounds; a fossil fuel consisting of the remains of ancient biomass.
Finite resource - cannot be replaced as it is used up.
What is a hydrocarbon?
A compound made up exclusively of hydrogen and carbon atoms
What are alkanes?
Saturated hydrocarbons of a general formula
What is a homologous series?
Series of compounds with same general formula, same functional groups and similar chemical properties.
Describe the combustion of hydrocarbons
- Exothermic reaction occurring when
hydrocarbons are reacted with oxygen. - Complete combustion produces carbon dioxide and water (carbon and
hydrogen atoms are completely oxidised). - Incomplete combustion produces carbon or carbon monoxide and water.
Describe the physical properties of alkanes
- First few in series are gases, then change to liquids, then to solids.
- In general, boiling points and viscosity increase as molecules get bigger.
- Volatility and flammability decrease as molecules get bigger.
- Poor reactivity.
Explain how fractional distillation of crude oil takes place
Step 1
- Crude oil is heated and vaporised.
Explain how fractional distillation of crude oil takes place
Step 2
- Vapor rises up the fractionating column (tower).
Explain how fractional distillation of crude oil takes place
Step 3
- The column is hotter at the bottom and cooler at the top.
Explain how fractional distillation of crude oil takes place
Step 4
- Hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points.
Explain how fractional distillation of crude oil takes place
Step 4
- Large molecules, high boiling points - collected at the bottom.
Explain how fractional distillation of crude oil takes place
Step 5
- Small molecules, low boiling points - collected at the top.
Explain how fractional distillation of crude oil takes place
Step 6
- This gives fractions, which can be used in various ways.
What is cracking?
When large hydrocarbons are thermally broken down into smaller and useful molecules
What type of reaction is cracking?
Thermal decomposition
What are the conditions for cracking?
Reactant heated to vapor, passed over a hot catalyst (catalytic cracking) or heated to vapor, mixed with steam and heated to high temperatures (steam cracking)
How are the products of cracking used?
The products are alkanes and alkenes – used as polymers and starting materials for synthesis.
What is an alkene?
Unsaturated hydrocarbon. Contains a C=C bond.
What is the general formula for alkenes
What is the test for alkenes?
Add bromine water. Colour change occurs from orange to colourless.
Describe the combustion of alkenes
They burn with smoky flames due to incomplete combustion
Describe addition reactions of alkenes
Addition atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.
What happens in the addition reaction between carbon and hydrogen
With hydrogen - hydrogenation; requires a higher temperature and a nickel catalyst
What happens in the addition reaction between carbon and steam
With steam - hydration; requires high temperature, pressure, and concentrated phosphoric acid (H3PO4) as a catalyst
What happens in the addition reaction between carbon and Br2/Cl2/I2
addition of halogens
What is an alcohol?
An organic compound that contains an -OH functional group
State characteristics of methanol, ethanol,propanol and butanol
- Dissolve in water to form a neutral solution.
- React with sodium to form hydrogen.
- Burn in oxygen.
- React with carboxylic acids in presence of acid catalyst to form esters.
Oxidation of the alcohols leads to…?
Carboxylic acids
What are some uses of alcohols?
- Fuels
- Solvents
- Drinks
State the conditions required for fermentation of glucose
30 degrees Celsius, aqueous solution of the glucose, absence of air, yeast added;
What is the equation for the fermentation of glucose
C6H12O6 → 2x CH3CH2OH + 2x CO2
What are carboxylic acids?
Organic compounds that contain a COOH functional group
State 4 of the characteristics of carboxylic acids
- Dissolve in water to form an acidic solution (contains H+ ions)
- React with metal carbonates to form carbon dioxide
- React with alcohols with an acid catalyst to produce esters
- React with metals to give off hydrogen gas
What type of acid is carboxylic acid?
It is a weak acid.
Explain why carboxylic acids are weak acids?
They are partially dissociated in water, thus the pH of a carboxylic acid in solution is not as low as a solution of a strong acid of the same concentration.
What is an ester and how is it formed?
An organic compound containing a -COO- functional group, formed from carboxylic acid and alcohol in the presence of a sulfuric acid catalyst.
What is a characteristic in an ester
about this class of compounds?
They have a fruity smell.
What is a polymer?
A polymer is a long chain molecule which is made by lots of smaller molecules joining together.
How do molecules containing C=C bond form polymers?
C=C bonds open up and many smaller molecules (monomers) join together to form a chain (a polymer). No other products are made.
It is called an “addition polymerisation” reaction.
Give 3 examples of addition polymers and their uses.
Polyethene
Poly)tetrafluoroethene (PTFE)
Poly)chloroethene (polyvinylchloride, PVC)
What is polyethene used in
plastic bags
What is Poly)tetrafluoroethene (PTFE) used in
teflon surfaces, for use in non-stick kitchenware
What is (Poly)chloroethene (polyvinylchloride, PVC) used in
Water pipes
What is a repeating unit of a polymer?
It is a smallest structure which, upon numerous translations, yields the structure of the polymer.
How to draw polymers
In addition polymers: to draw it, take a monomer, change C=C to C-C and show additional single bonds extending away from these carbons.
What is a condensation polymer?
It is a polymer made in condensation polymerisation.
How is a condensation polymer made
In this reaction, many molecules join together; the polymer is formed, but also a small molecule is released, e.g. H2O, HCl.
What are the two main groups of polymers
name them and give relevant examples.
Polyesters, e.g. terylene.
Polyamides, e.g. Nylon.
What is an amide bond?
An amide bond is similar to the ester bond, with O replaced by N, e.g. (C=O)-NH2
Just like an ester, it contains the C=O group.
What is an amino acid?
It is an organic compound that contains both a carboxylic acid functionality (COOH) and an amine functional group (-NH2).
How do amino acids make proteins?
By numerous condensation polymerisation reactions; proteins are polymers made of amino acids (monomers).
What are polypeptides?
*Polypeptides are also made by condensation polymerisation of amino acids, but are shorter than proteins. One could think about proteins as a product of many polypeptide chains bonded together.
What are carbohydrates?
They are organic molecules made of C,H, and O. They are biologically relevant, e.g. starch and cellulose.
Both of these are polymers made of glucose (other carbohydrate) monomers. Their structures differ in the way the glucose molecules are joined together.
What is DNA?
DNA (deoxyribonucleic acid) is a material that makes up chromosomes - cell structures that store genetic information.
What is DNA is role and structure
DNA is made of two polymer chains that are held together in a double helix.
Each polymer chain can be made from 4 different monomers - nucleotides.
Order of crude oil fractions from coolest to Hot
Liquefied petroleum gases (LPG)
Petrol
Kerosene
Diesel
Heavy fuel oil
Bitumen
Uses of LPG
Cooking
Vehicles
Industrial applications
Uses of naptha
To treat laundry stains and hand wash clothes
Uses of Petrol
Fuel for transportation (gasoline, diesel, jet fuel)
Heating homes
Generating electricity
Uses of Kerosen
Cooking
lighting
heating
What is the formula for Alkenes
What is the formula for Alkanes
What is the homolgous series
How many Carbons (C) and Hydrogens (H) are in Ethene
Alkene
C = 2
H = 4
How many Carbons (C) and Hydrogens (H) are in Propene
Alkene
C = 3
H = 6
How many Carbons (C) and Hydrogens (H) are in butene
Alkene
C = 4
H = 8
How many Carbons (C) and Hydrogens (H) are in pentene
(Alkene)
C = 5
H = 10
How many Carbons (C) and Hydrogens (H) are in Methane
Alkane
C = 1
H = 4
How many Carbons (C) and Hydrogens (H) are in Ethane
Alkane
C = 2
H = 6
How many Carbons (C) and Hydrogens (H) are in Propane
Alkane
C = 3
H = 8
How many Carbons (C) and Hydrogens (H) are in Butane
Alkane
C = 4
H = 10
What is Hydrogenation
Hydrogenation is the addition of hydrogen across the alkene double bond
What is an example of Hydrogenation
polyunsaturated fats being changed into saturated fats eg
liquid vegetable oils into solid edible fats or margarines
What is a reagant
A reagent is a compound or mixture added to a system to start or test a chemical reaction.
What is the reagent in Hydrogenation
What are the conditions required for Hydrogenation
Heat
What is the catalyst in Hydrogenation
Nickel metal (in the form of fine grains known as Raney nickel)
What is the type of reaction is Hydrogenation
Addition / hydrogenation
What is an example of Hydrogenation
hydrogen can be added to either but-1-ene or but-2-ene to form butane.
What is an example of Hydrogenation
hydrogen can be added to either but-1-ene or but-2-ene to form butane.
What are the conditions required for Hydration with steam
330•C
60-70 atm
Acid catalyst
What are the conditions required for Hydration
150•C and nickel catalyst
What is the polymersation of ethene
What is the polymersation of butene
