Organic Chemistry

Question 1

What is crude oil?

Answer 1

Crude oil is a fossil fuel formed from the remains of sea creatures. It is a finite resource and consists of hydrocarbons, mainly alkanes.

Question 2

What are hydrocarbons?

Answer 2

Hydrocarbons are compounds that contain only hydrogen and carbon atoms

Question 3

What are alkanes? General Formula? Functional group?

Answer 3

Alkanes are saturated hydrocarbons with single covalent bonds between the carbon atoms and single covalent bonds to the hydrogens.

C(n) H(2n+2)
Alkanes lack a functional group

Question 4

What are the products of complete and incomplete combustion? Carbon Monoxide?

Answer 4

Complete = Carbon Dioxide and Water
Incomplete = Carbon Monoxide and Water

Carbon Monoxide is toxic and cannot be seen or smelled

Question 5

What are the properties of short and long alkenes?

Answer 5

Longer alkenes have higher boiling points, stronger intermolecular forces, more viscous

Shorter alkenes are more volatile, less viscous, and lower boiling points

Question 6

What are alkenes? General formula? Functional group?

Answer 6

Alkenes are unsaturated hydrocarbons containing a carbon carbon double covalent bond. Alkenes are generally more reactive than alkanes.

C(n) H(2n)
C=C is the functional group

Question 7

What is a functional group?

Answer 7

A functional group is an atom or group of atoms that gives organic compounds their characteristic reactions

Question 8

What is a homologous series? Examples?

Answer 8

Homologous series are a group of related organic compounds with the same functional group. They all have the same general formula. Examples are alcohols, alkenes, and alkanes

Question 9

How do alkenes react in combustion?

Answer 9

Alkenes burn with a smoky, yellow, luminous flame compared to alkanes. This is because they are usually involved in incomplete combustion. This is because they release less energy per mole than alkanes in combustion

Question 10

What are addition reactions? How do they help test for alkenes?

Answer 10

An atom/ group of atoms can combine with an alkene molecule to form a larger molecule. Alkenes react with bromine water turning the solution from orange/brown to colourless. Alkanes do not react

Question 11

What is hydrogenation?

Answer 11

Alkenes are unsaturated so more hydrogen can be added across the double bond to make them saturated alkanes. This reaction is known as hydrogenation and takes place at 60 degrees Celsius with a nickel catalyst

Question 12

What is hydration?

Answer 12

Hydration is the addition of water. To hydrate ethene, the reaction is at over 100 degrees Celsius, at high pressure, and uses concentrated phosphoric acid as a catalyst

Question 13

What are alcohols?

Answer 13

Alcohols contain the functional group OH. Alcohols have the general formula C(n)H(2n+1)OH
Alcohols take name from alkanes but have the additional OH functional group

Question 14

How do alcohols become carboxylic acids?

Answer 14

Chemical oxidising agents such as acidified potassium dichromate can oxidise alcohols to carboxylic acids. The same reaction takes place if ethanol is exposed to air

Ethanol + Oxygen atoms from oxidising agents ——> Ethanoic Acid + Water

Question 15

Where is ethanol used?

Answer 15

Beverages
Fuels
Deodorant
Antiseptic

Question 16

What are the advantages and disadvantages of hydration conditions of ethene?

Answer 16

• Hydrating ethene uses cracking from crude oil so the materials are non-renewable
• Moderately high temperature and pressure which are harsh reaction conditions
• Phosphoric Acid Catalyst
• 100% atom economy

Question 17

What are the advantages and disadvantages of fermentation conditions of ethanol?

Answer 17

• Raw materials of fermentation are renewable
• Yeast cells have enzymes which catalyse reactions
• Low yield and atom economy
• Needs to be purified in fractional distillation
• 35 degrees Celsius is optimum temperature (Easy)

Question 18

What are carboxylic acids?

Answer 18

Carboxylic acids have the functional group COOH. The general formula is C(n) H(2n+1) COOH
They always produce carbon dioxide in reactions

Question 19

What is a monomer?

Answer 19

A monomer is a small molecule which combines with many other monomers to form a polymer

Question 20

What is a polymer?

Answer 20

A polymer is a large molecule formed with many thousands of repeating units of small molecules called monomers

Question 21

What is addition polymerisation? Conditions?

Answer 21

Addition polymerisation is a reaction where many alkene monomers join together to form a long chain polymer. Requires hight temperature and a catalyst

Question 22

What happens in a condensation reaction?

Answer 22

In a condensation reaction, two molecules react to form one larger molecule and one smaller molecule. The smaller molecule is often water or hydrogen chloride

Question 23

What is condensation polymerisation? Conditions?

Answer 23

Condensation polymerisation is the joining of monomers with the loss of a small molecule (usually water)
High Temperature, Sulfuric Acid

Question 24

What is ethanediol? What is dicarboxylic acid?

Answer 24

Ethanediol is an alcohol with 2 functional groups. Dicarboxylic acid contains 2 functional groups

Question 25

Comparison of Addition & Condensation Polymerisation

Answer 25

Addition // Condensation
Monomer with carbon double bond // Monomers with two functional groups
Backbone of polymer is continuous carbon chain // Polymer contains ester or amide bond
Only polymer product // Small molecule side product
Requires catalyst and high temperature // Requires catalyst and high temperature

Question 26

What is cracking? Conditions?

Answer 26

Chemical reaction that converts large alkane molecule into smaller alkane and alkene molecules.
High Temp (600-700), Alumina/Silica Catalyst

Question 27

Why is cracking done?

Answer 27

Cracking breaks down larger alkane molecules which are less useful into smaller alkane molecules which are more useful

Question 28

How do chemical cells work?

Answer 28

Exothermic reactions in the cell develop a potential difference or voltage between its two ends. These are then connected to a circuit where current flows

Question 29

What is the purpose of a fuel cell?

Answer 29

A fuel cell produces electricity through a chemical reaction between a fuel and oxygen, without combustion happening

Question 30

How does a hydrogen-oxygen fuel cell work?

Answer 30

At the anode, hydrogen molecules lose electrons. They pass through a proton exchange membrane to the other side. Electrons from hydrogen travel through an external circuit to the other side too. Hydrogen ions combine with oxygen and electrons to form water vapour

Question 31

What is the half equation at the anode and cathode of the hydrogen fuel cell?

Answer 31

2H2 —> 4H(+) + 4e(-)

4H(+) + O2 + 4e(-) —> 2H2O