Organic Chemistry

Question 1

What is a hydrocarbon

Answer 1

A molecule containing only hydrogen and carbon

Question 2

What is the emperical formula

Answer 2

The formula showing the simplest ratio between atoms in a molecule

Question 3

What is the molecular formula

Answer 3

The formula showing the actual number of atoms in a molecule

Question 4

What is the structural formula

Answer 4

Describes which atoms are bonded to which, and where about they are

Question 5

What is the structural formula

Answer 5

Describes which atoms are bonded to which, and where about they are

Question 6

Graphical or displayed formula

Answer 6

A visual representation of a molecule

Question 7

General formula

Answer 7

Shows the ratio of atoms in a family of compounds

Question 8

What is a homologous series

Answer 8

A group of organic compounds with similar chemical properties and structural features

Question 9

What is a saturated hydrocarbon

Answer 9

A hydrocarbon where all the carbon atoms have single bonds

Question 10

What is an unsaturated hydrocarbon

Answer 10

A hydrocarbon where the carbon atoms have multiple bonds (double or triple)

Question 11

What is an isomer

Answer 11

A molecule with the same molecular formula but a different structural formula

Question 12

What is a fuel

Answer 12

A substance which releases energy in an exothermic reaction (combustion)

Question 13

What is the product of a complete combustion reaction of a hydrocarbon

Answer 13

Carbon dioxide + Water

Question 14

What is the product of an incomplete combustion reaction of a hydrocarbon

Answer 14

Carbon monoxide + Water

Question 15

Difference between a complete and incomplete combustion reaction

Answer 15

• Complete takes place when there is sufficient oxygen
• Incomplete takes place when there is insufficient oxygen
• Products are different
  …Products of complete is CO2 and H20
  …Products of incomplete is CO and H20

Question 16

Give examples of fossil fuels

Answer 16

• Coal
• Oil
• Natural gases

Question 17

What are the negative impacts of burning fossil fuels

Answer 17

• Gives off pollution
• Contributes to global warming

Question 18

What are the 3 types of reactions

Answer 18

• Substitution
• Addition
• Combustion

Question 19

What is a substitution reaction

Answer 19

When 1 functional group is replaced by another

Question 20

What is an addition reaction

Answer 20

When the reactants join to form a larger molecule with no other product

Question 21

What is a combustion reaction

Answer 21

A burning reaction. An organic substance reacts with Oxygen to form CO2 (or CO for incomplete combustion reactions) and H2O

Question 22

What happens when an alkane reacts with bromine

Answer 22

Alkane + bromine –> bromoalkane + hydrogen bromide

Methane + bromine –> bromomethane + hydrogen bromide

Question 23

What happens when an alkene reacts with bromine

Answer 23

Alkene + bromine –> Dibromomalkane

Ethene + bromine –> Dibromoethane

Question 24

How can you test for an alkene

Answer 24

Use bromine water. Alkene + bromine (orange) –> dibromoalkene (colourless)

Question 25

What is fractional distillation?

Answer 25

Fractional distillation is a method of separating crude oil into different hydrocarbon fractions

Question 26

Give each step of fractional distillation

Answer 26

1. Crude oil is heated at 350deg at the bottom of the fractioning column 2. The vapour will rise 3. The large hydrocarbons with very high boiling points will condense into a liquid and will be tapped off at the bottom of the fractioning column 4. As the vapour rises, each hydrocarbon fraction will condense at its boiling point 5. The small hydrocarbons with very low boiling points will be collected at the top of the fractioning column as gases

Question 27

What are the fractions called from bottom to top and what are their uses

Answer 27

1. Bitchumen - Used for roofs and roads 2. Fuel oil - Fuel for ships, power stations 3. Diesel - Fuel for cars, lorries and buses 4. Kerosene - Fuel for aircrafts 5. Gasoline - Fuel for cars 6. Refinery gases - Bottled gas. In liquid form used for domestic heating and cooking

Question 28

What happens to viscosity as hydrocarbons get larger

Answer 28

The larger the hydrocarbon, the more viscous it is

Question 29

When happens to colour as hydrocarbons get larger

Answer 29

The larger the hydrocarbon, the darker it is

Question 30

What happens to volatility as hydrocarbons get larger

Answer 30

The larger the hydrocarbon, the less volatile it is (volatility is tendency to vapourise)

Question 31

What happens to mpt/bpt as hydrocarbons get larger

Answer 31

The larger the hydrocarbon, the higher their mpt/bpt as there are more bonds to break

Question 32

What happens to flammability as hydrocarbons get larger

Answer 32

The larger the hydrocarbon, the less flammable it is. More intermolecular forces to break so less volatile, higher bpt and less flammable

Question 33

Why is carbon monoxide poisonous and how is it dangerous

Answer 33

Carbon monoxide binds well with the haemoglobin and therefore the haemoglobin cannot bind with the oxygen and carbon dioxide Carbon monoxide is an odourless, colourless gas which can cause dizziness, loss of consciousness and death

Question 34

What is cracking

Answer 34

Cracking is the breaking down of larger, less useful alkanes into smaller, more useful ones

Question 35

What happens when cracking large alkanes

Answer 35

A smaller alkane is formed, as well as an alkene

Question 36

What is the general formula of an alkane

Answer 36

CnH2n+2

Question 37

What is the general formula of an alkene

Answer 37

CnH2n

Question 38

Other than CO2 and CO, what other pollutants may be given off when burning fuels

Answer 38

- Sulfur dioxide - Oxides of nitrogen (NOx)

Question 39

When is sulfur dioxide given off as a pollutant

Answer 39

Some fuels like coal contain sulfur When they are burnt, this sulfur reacts with the oxygen to form sulfur dioxide

Question 40

When are oxides of nitrogen given off as pollutants

Answer 40

In car engines, nitrogen reacts with oxygen in the air at high temperatures and pressure forming oxides of nitrogen

Question 41

What are the dangers of oxides of nitrogen and sulfur dioxide

Answer 41

- Acid rain - Breathing problem for people with asthma

Question 42

What are the dangers of acid rain

Answer 42

- Changes pH of soil - Can corrode buildings made of limestone - Damage trees

Question 43

What type of gas is CO2

Answer 43

A greenhouse gas

Question 44

How can CO2 contribute to global warming

Answer 44

1. The Sun's energy enters the atmosphere and heats up the Earth's surface 2. Some of this heat is absorbed by earths surface and some is radiated back into the atmosphere as infrared radiation 3. CO2 absorbs some of this heat and re-radiates it to the Earth's surface, trapping the heat and warming the planet

Question 45

What is the test for CO2

Answer 45

Limewater