Organic Chemistry Part 1

Question 1

What is crude oil formed from?

Answer 1

The decomposition of tiny creatures that lived in the sea more than 100 million years ago

Question 2

What type of rocks are crude oil formed in?

Answer 2

Porous sedimentary rocks

Question 3

What is crude oil (chemical terms)?

Answer 3

A mixture of hydrocarbons

Question 4

What is a hydrocarbon made up of?

Answer 4

Only Hydrogen & Carbon

Question 5

How can we separate crude oil into its products?

Answer 5

By using fractional distillation

Question 6

What is crude oil classed as?

Answer 6

A fossil fuel

Question 7

What is the name of most compounds in crude oil?

Answer 7

Alkanes (saturated hydrocarbons)

Question 8

What does saturated mean in the context of hydrocarbons?

Answer 8

They are only contain single covalent bonds

Question 9

What is a homologous series?

Answer 9

A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula

Question 10

What are the first 6 members of the alkane homologous series?

Answer 10

Methane
Ethane
Propane
Butane
Pentane
Hexane

Question 11

What is the chemical formula of methane?

Answer 11

CH₄

Question 12

What is the chemical formula of ethane?

Answer 12

C₂H₆

Question 13

What is the chemical formula of propane?

Answer 13

C₃H₈

Question 14

What is the chemical formula of Butane?

Answer 14

C₄H₁₀

Question 15

What is the chemical formula of pentane?

Answer 15

C₅H₁₂

Question 16

What is the chemical formula of Hexane?

Answer 16

C₆H₁₄

Question 17

What is the general formula for the homologous series of alkanes?

Answer 17

CnH2n + 2

Question 18

What are the general rules that compounds in a homologous series have to follow?

Answer 18

1. Have the same general formula
2. Contain the sae functional group (this determines how the chemical reacts)
3. Share similar chemical properties
4. Follow a trend in physical properties

Question 19

What is an isomer?

Answer 19

Isomers are compounds that have the same molecular formula but a different displayed formula

Question 20

What does molecular formula show?

Answer 20

How many atoms of each element there are in a molecule

Question 21

What does displayed formula show?

Answer 21

All the bonds between all of the atoms in a molecule

Question 22

How many isomers are there for pentane?

Answer 22

3

Question 23

How many isomers are there for hexane ?

Answer 23

5

Question 24

What is crude oil more useful for?

Answer 24

The fractions it can be separated into

Question 25

How can you obtain the six different fractions of crude oil?

Answer 25

By using fractional distillation

Question 26

Explain how to distill crude oil.

Answer 26

The oil mixture is heated and begins to evaporate. Vapour enters the fractionating column (the column is hot at the bottom and cool at the top). The vapour recondenses in the column at first and falls back into the flask. (The process is repeated). Once the top of the column reaches the boiling point of the first fraction, the vapour evaporates and goes into the condenser and it collected as a liquid in a conical flask. Fractions are collected at different temperatures in separate flasks.

Question 27

What are the main fractions obtained from crude oil?

Answer 27

Refinery Gases Gasoline Kerosene Diesel Fuel oil Bitumen

Question 29

What is the use of refinery gases?

Answer 29

Used as fuel for domestic heating and cooking.

Question 30

What is the use of gasoline (petrol)?

Answer 30

Powers internal combustion engines in vehicles.

Question 31

What is the use of kerosene?

Answer 31

Serves as jet fuel for aircraft.

Question 32

What is the use of diesel oil?

Answer 32

Fuels diesel engines in lorries and some cars.

Question 33

What is the use of fuel oil?

Answer 33

Provides energy for ships and power stations.

Question 34

What is the use of bitumen?

Answer 34

Used in road surfacing and roofing.

Question 35

What is the trend in colour of the crude oil fractions?

Answer 35

The colour darkens as you go down

Question 36

What is the trend is boiling point of the crude oil fractions?

Answer 36

The boiling point increases as you go down the group

Question 37

What is the trend in viscosity of the crude oil fractions?

Answer 37

As you go down the group the fractions become more viscous

Question 38

What is the trend in ease of lighting as you go down the fractions?

Answer 38

They become harder to light

Question 39

What is released when fuel is burnt? (One of the main purposes)

Answer 39

Thermal energy

Question 40

Which of the alkanes are gases at room temperature?

Answer 40

Methane, Ethane, Propane, Butane

Question 41

Which of the alkanes are liquids at room temperature?

Answer 41

Propane, Hexane

Question 42

Why do alkanes become more viscous as you go down the fractions?

Answer 42

The fractions have longer carbon chains and they become entangled with one another

Question 43

What is different about industrial fractional distillation than normal fractional distillation?

Answer 43

Much larger scale Temperatures at different points of the fractioning column are carefully controlled Gasses condense when they reach their boiling point Higher boiling points are collected at bottom

Question 44

Describe how crude oil is separated into fractions in industry?

Answer 44

Crude oil is vaporised and enters the bottom of the column. The bottom is hot at the bottom, and cool at the top (a temperature gradient is present). The alkanes rise up the column and condense at their boiling point (as it only gets cooler as you go up the column). Then they are 'tapped' at the column in different fractions

Question 45

What are the products of complete combustion?

Answer 45

Carbon dioxide Water

Question 46

In an experiment to test for the products of complete combustion, why is the funnel face down?

Answer 46

To catch as much of the products as possible

Question 47

In an experiment to test for the products of complete combustion, what is the purpose of the water pump?

Answer 47

To create a pressure drop to form suction to pull the hydrogen, carbon and water vapour through the system.

Question 48

In an experiment to test for the products of complete combustion, why is the U-Tube surrounded by ice?

Answer 48

To attempt to condense the water to make it easier to test for its presence with the anhydrous copper sulphate

Question 49

How can you test for the presence of carbon dioxide?

Answer 49

Use limewater If present goes from clear to cloudy

Question 50

How can you test for the presence of Water?

Answer 50

Anhydrous copper sulphate If present goes from white to blue Anhydrous cobalt chloride If present goes from blue to pink

Question 51

What is incomplete combustion?

Answer 51

Combustion where there isn't enough oxygen

Question 52

What is soot?

Answer 52

Carbon in the form of a powder

Question 53

What can be observed when a pot is held in a bunsen burner with the air hole open?

Answer 53

No soot is present

Question 54

What can be observed when a pot is held in a bunsen burner with the air hole closed?

Answer 54

Soot (carbon as a black powder) was deposited on the pot

Question 55

What dangerous products can be formed when a hydrocarbon fuel is burned in a limited supply of air?

Answer 55

Soot Carbon monoxide

Question 56

What is acid rain caused by?

Answer 56

Nitrogen dioxide Sulphur dioxide Both products of incomplete combustion

Question 57

How does nitrogen (N₂) form nitrogen (NO₂) dioxide?

Answer 57

In engines the heat and pressure causes O₂ and N₂ to react together

Question 58

How does sulphur (S₂) form sulphur (SO₂) dioxide?

Answer 58

Sulphur burns in oxygen (when heated) and gives sulphur dioxide

Question 59

How do sulphur dioxide and nitrogen dioxide lead to acid rain?

Answer 59

When they are dissolved in rainwater

Question 60

What are the main problems with acid rain?

Answer 60

Can lead to substances eroding easily Can make soil to acidic - kills plants