C8 - Organic Chemistry 1

Front 1

Name and draw the structures of methane, ethane, ethene, ethanol, ethanoic acid and their products

Back 1

Methane, ethane, propane and butane are all alkanes (only single bonds) and consist of 1, 2, 3 and 4 carbons respectively. The formula for finding the number of hydrogen atoms in them is given through the equation 2n+2, with n being the number of carbon atoms.

Methene, ethene, propene and butene are alkenes (contain double bonds) and contain the same amount of carbon atoms as their alkane counterparts, but the number of hydrogen atoms they contain is time given through the equation 2n.

Alcohols, such as ethanol, contain no double bonds (2n+2) and an -O-H link as opposed to just an -H link on one of the carbons.

Carboxylic acids, such as ethanoic acid, contain a double bond (2n) with an oxygen atom, as well as an O-H link, just like alcohols.

Front 2

State the type of compound present, given a chemical name ending in -ane, -ene, -ol, or -oic acid or a molecular structure

Back 2

Alkanes and alkenes contain only carbon and hydrogen atoms. Alcohols contain an extra oxygen atom, and carboxylic acids have another extra one.

Front 3

Name and draw the structures of the unbranched alkanes, alkenes (not cis- trans),alcohols and acids containing up to four carbon atoms per molecule

Back 3

Equation for alkanes - 2n+2 - only single bonds

Equation for alkenes - 2n - one double bond

Front 4

Name and draw the structural formulae of the esters which can be made fromunbranched alcohols and carboxylic acids, each containing up to four carbonatoms

Back 4

Alcohols, such as ethanol, contain no double bonds (2n+2) and an -O-H link as opposed to just an -H link on one of the carbons.

Carboxylic acids, such as ethanoic acid, contain a double bond (2n) with an oxygen atom, as well as an O-H link, just like alcohols.

Front 5

Name the three main fuels

Back 5

Coal, natural gas, petroleum

Front 6

Name the main constituent of natural gas

Back 6

Methane

Front 7

Describe petroleum as a mixture of hydrocarbons and its separation into useful fractions

Back 7

The fossil fuels coal, petroleum and natural gas all contain hydrocarbons. Fractional distillation is used to separate the hydrocarbon molecules in petroleum into groups that have similar boiling points. These groups of molecules are called fractions, and each contains hydrocarbons having a certain range of carbon atoms.

Front 8

Describe the properties of molecules within a fraction

Back 8

Each fraction has particular properties. As the number of carbon atoms increases, the boiling and melting points increase, the density increases, and the flammability increases as well.

Front 9

Name the uses of the fractions:

* Refinery gas
* Gasoline
* Naphtha
* Kerosene
* Diesel oil
* Fuel oil
* Lubricating fraction
* Bitumen

Back 9

* Refinery gas - bottled as gas for heating and cooking
* Gasoline - fuel for cars (a.k.a petrol)
* Naphtha - making chemicals, especially plastics
* Kerosene - fuel for jet aircraft (a.k.a paraffin)
* Diesel oil - fuel for lorries and tractors
* Fuel oil - fuel for power stations, ships, and home heating
* Lubricating fraction - lubricants, waxes, and polishes
* Bitumen - making road surfaces

Front 10

Describe the concept of homologous series

Back 10

A homologous series is a family of similar compounds with similar chemical properties due to the presence of the same functional group

Front 11

Describe the general characteristics of a homologous series

Back 11

We can give each homologous series a general formula which applies to all members of the homologous series. For example, all member of the alkane homologous series have the general formula C(n)H(2n+2)

The memebers of a homologous series have very similar chemical properties, and the physical properties in a homologous series change in a regular way - for example, the boiling points of alkanes increase with the increase of carbon atoms.

Front 12

Describe and identify structural isomerism

Back 12

The carbon chain in alkanes and other organic compounds can be branched. 2-Methylpropane has four carbon atoms and the same molecular formula as butane, C₄H₁₀, but it isn't butane because the carbon atoms are arranged differently.

Compounds with the same molecular formula but with a different structural formula are called isomers.

Front 13

Describe the properties of alkanes as being generallyunreactive, except in terms of burning

Back 13

All alkanes are colourless gases, liquids or solids. Alkanes are generally unreactive compounds and do not react with acids or alkalis. Alkanes do burn with a clean blue flame if there is plenty of oxygen or air present - complete combustion.

C₃H₈ + 5O₂ --> 3CO₂ + 4H₂O

Front 14

Describe the bonding in alkanes

Back 14

Alkanes are hydrocarbons which have only single covalent bonds in their structure. We call them saturated hydrocarbons because no more atoms can be added to their molecules.

Front 15

Describe substitution reactions of alkanes with chlorine

Back 15

A chlorine atom can replace a hydrogen atom in an alkane in a type of reaction called a substitution reaction. This reaction is also photochemical as it needs UV or natural light.

ex) CH₄ + Cl₂ --> CH₃Cl + HCl

methane + chlorine --> chloromethane +

hydrochloric acid

Front 16

Describe the manufacture of alkenes and of hydrogen by cracking

Back 16

We can break down larger hydrocarbons into smaller, more useful hydrocarbons. This is called cracking. Heat and an aluminium oxide catalyst are needed for cracking. Cracking an alkane can produce a smaller alkane, alkenes and hydrogen.

ex) C₂H₆ --> C₂H₄ + H₂

Front 17

Distinguish between saturated and unsaturated hydrocarbons

Back 17

The alkenes are a homologous series of hydrocarbons whose names end in -ene. We call them unsaturated hydrocarbons because they have a C=C double bond. They do not have the maximum number of hydrogen atoms around each carbon atom - more atoms can be added.

We can use aqueous bromine to test if a hydrocarbon is saturated or not. Bromine water is yellow/orange in colour. If bromine water is decolourised with the addition of a hydrocarbon, it is unsaturated. If it retains its colour, the hydrocarbon is saturated.

Front 18

Describe the formation of poly(ethene) as an example of addition polymerisation ofmonomer units

Back 18

The process of joining monomers together to form polymers is called polymerisation. Polymers are often formed by addition reactions. We call this type of polymerisation, where no other substance is formed, addition polymerisation.

When alkene molecules react, one of the C=C double bonds breaks and joins with its neighbouring molecule.

Front 19

Describethe properties of alkenes in terms of addition reactions with bromine, hydrogenand steam

Back 19

Many of the reactions of alkenes are called addition reactions. In an addition reaction, two reactants add together to form only one product.

ex) C₂H₄ + Br₂ --> C₂H₄Br₂

ethene + bromine --> 1,2-dibromoethane

Hydrogen reacts with alkenes to form alkanes. This reaction needs a nickel catalyst and heat.

ex) C₂H₄ + H₂ --> C₂H₆

ethene + hydrogen --> ethane

Steam reacts with alkenes to form alcohols. A high temperature and high pressure are needed for this reaction, as well as a phosphoric acid catalyst.

ex) C₂H₄ + H₂O --> C₂H₅OH

Front 20

Describe the release of heat energy by burning fuels

Back 20

All fuels give out heat energy when combusted, and these combustions are exothermic reactions. However, they are polluting and contribute to global warming, except hydrogen, which is a fuel that is non-polluting.

Front 21

Describe radioactive isotopes, such as 235U, as a source of energy

Back 21

Many nuclear power stations use the radioisotope uranium-235 as a nuclear fuel. The U235 is bombarded with high-speed neutrons. The collisions cause the nucleus of the U235 to split. When this happens a large amount of energy is released. More neutrons are produced and the 'new' neutrons then hit other U235 atoms to split them.

Front 22

Describe the formation of nylon, a polyamide, by condensation polymerisation.

Back 22

Nylon is typical polyamide. The two types of monomer that form a polyamide are carboxylic acids and amines. An amine is a compound with an -NH₂ functional group. A carboxylic acid reacts with an amine to form an amide.

This type of reaction, when two molecules join together and a small molecule is eliminated, is called a condensation reaction.

Front 23

Describe the formation of terylene, a polyester, by condensation polymerisation.

Back 23

Terylene is a typical polyester. The two types of monomer that form a polyester are carboxylic acids and alcohols. An ester linkage is formed.

This reaction is also a condensation reaction.

Front 24

Name proteins and carbohydrates as constituents of food

Back 24

The main classes of food molecules that give us energy are carbohydrates and fats.

Front 25

Describe proteins as possessing the same (amide) linkages as nylon but with differentunits

Back 25

Proteins have the same amide linkages as nylon. But instead of being made from two different monomers, proteins are made up from twenty. These monomers are amino acids. All amino acids have the amine (-NH₃) and carboxylic acid (-COOH) groups in common, but the side chains in each of the 20 amino acids are different.

Front 26

Describe the structure of proteins

Back 26

When proteins are made, an amide link is formed by the reaction of the amine group of one amino acid with the carboxylic acid group of the next amino acid. This is also a condensation reaction.

Front 27

Describe the hydrolysis of proteins to amino acids

Back 27

We can break down proteins to amino acids by heating them with hydrochloric acid. Heat is also needed for this reaction.

Protein + water --> amino acids

We call this a hydrolysis reaction. In a hydrolysis reaction, a compound reacts with water and breaks down to form two or more products.

Front 28

Describe complex carbohydrates in terms of
 a large number of sugar units

Back 28

Carbohydrates are made up of carbon and water (hydrogen and oxygen). The empirical formula for a carbohydrate is Cᵪ(H₂O)ᵧ.

The monomers that form complex carbohydrates can be represented by the formula HO- ⃞-OH.

Front 29

Describe the hydrolysis of complex carbohydrates (e.g. starch), by acids or enzymes togive simple sugars

Back 29

When we heat polysaccharides with hydrochloric acid they are hydrolysed to simple sugars. When starch is hydrolysed, the linkages break and simple sugars are formed.

Front 30

Describe the fermentation of simple sugars to produce ethanol and carbon dioxide

Back 30

The fermentation of glucose produces ethanol and carbon dioxide. The reaction takes place in the absence of air - it is anaerobic.

C₆H₁₂O₆ --> 2C₂H₅OH + 2CO₂

glucose --> ethanol + carbon dioxide

Front 31

Describe in outline the usefulness of chromatography in separating and identifying theproducts of hydrolysis of carbohydrates and proteins

Back 31

The simple sugars formed by the hydrolysis of polysaccharides can be identified using paper chromatography. Because sugars are colourless, we have to use a locating agent so they show up on a chromatogram.

However, you cannot always identify a sugar or amino acid from a chromatogram as some have similar Rf values. We can overcome this by using two-dimensional chromatography.

* We carry out the chromatography as usual

* We allow the paper to dry, then turn it through 90° and carry out chromatography using a different locating solvent.
* Only then do we spray the chromatogram with a locating agent.