C14. Organic chemistry

Question 1

What do all organic compounds contain?

Answer 1

Carbon

Usually hydrogen as well.

Question 2

What types of fossil fuels product carbon dioxide on combustion?

Answer 2

Coal, natural gas and petroleum.

Question 3

What process separates petroleum into different fractions?

Answer 3

Fractional distillation.

Question 4

What is the main constituent of gas?

Answer 4

Methane

Question 5

What does petroleum consist of?

Answer 5

A mixture of hydrocarbons - carbon and hydrogen atoms.

Question 6

How does fractional distillation work?

Answer 6

Separates the hydrocarbons using the difference in their boiling points.

Question 7

State the trends of petroleum distillation.

Answer 7

1. Down = the boiling points increase (temp increases)
2. Down = the size of molecules is larger.
3. Down = density increases.
4. Down = flammability increases.

Question 8

State the use and temperature range of ‘refinery gas’.

Answer 8

Bottled as gas for heating and cooking.

Under 40C.

Question 9

State the use and temperature range of ‘gasoline’ (petrol).

Answer 9

Fuel for cars (petrol).

40 - 100C.

Question 10

State the use and temperature range of ‘naphtha’.

Answer 10

Making chemicals, especially plastics.

80 - 180C.

Question 11

State the use and temperature range of ‘kerosene’ (paraffin).

Answer 11

Fuel for jet aircraft and heating.

160 - 250C.

Question 12

State the use and temperature range of ‘diesel oil’.

Answer 12

Fuel for lorries and tractors.

250 - 300C.

Question 13

State the use and temperature range of ‘fuel oil’

Answer 13

Fuel for power stations, ships and home heating.

350 - 500C

Question 14

State the components and the uses of ‘residue’.

Answer 14

Lubricating oil - lubricants, waxes and polishes.

Bitumen - making road surfaces and sealing roofs.

Question 15

Name the characteristics of ‘alkanes’.

Answer 15

• Hydrocarbons
• Compounds of carbon and hydrogen only
• Single bonds (saturated)
• E.g. Methane, Ethane, Propane, Butane
• Not very reactive but they burn well
• Ends in -ane

Question 16

Name the characteristics of ‘alkenes’.

Answer 16

• Hydrocarbons
• Carbon and hydrogen only
• Have a double bond between two of the carbons (unsaturated)
• E.g. Ethene, Propene etc.
• Ends in -ene

Question 17

Name the characteristics of ‘alchohol’.

Answer 17

• Like alkanes
• One of the hydrogen atoms is replaced by OH
• E.g. Ethanol
• Ends in -ol

Question 18

What is a homologous series?

Answer 18

A group of compounds with the same functional group.

- Similar properties

Question 19

What is the formula for ‘alkanes’?

Answer 19

C(n)H(2n+2)

Question 20

What is the formula for ‘alkenes’?

Answer 20

C(n)H(2n)

Question 21

What is the formula for ‘alcohols’?

Answer 21

C(n)H(2n-1)OH

Question 22

What is the formula for ‘acids’?

Answer 22

C(n)H(2n-1)COOH

Question 23

What are the differences between homologous series?

Answer 23

• Chain length

- Physical properties gradually change due to increasing molecule size

Question 24

How do we form ethanol?

Answer 24

Fermentation - enzymes in yeast cells break down glucose to carbon dioxide and ethanol (exothermic)
From alkenes by addition of steam
C(6)H(12)O(6) -> 2C(2)H(5)OH + 2CO(2)

Question 25

What is another way of obtaining ethanol in a chemical factory?

Answer 25

Addition of the catalyst steam to ethene.

Question 26

Describe the combustion of ethanol.

Answer 26

Burns in oxygen to form carbon dioxide and water.

C(2)H(5)OH + 3O(2) -> 3H(2)O + 2CO(2)

Question 27

What the uses of ethanol?

Answer 27

As a fuel + solvent (dissolves many things and evaporates easily)

Question 28

Why is ethanol a better fuel than petrol?

Answer 28

It has already has an oxygen molecule in it.

Question 29

How do manufacture alkene?

Answer 29

Alkanes -> alkenes

- Heat alkane in the presence of a catalyst -> molecule breaks down