C14) Organic Chemistry

Question 1

What is a hydrocarbon?

Answer 1

ONLY contains hydrogen and carbon

Question 2

What is an Alkane?

Answer 2

-contains single bonds
- saturated

Question 3

What is an Alkane?

Answer 3

-contains single bonds
- saturated

Question 4

What is an Alkene?

Answer 4

-contains at least one double bond
- unsaturated

Question 5

What does saturated mean?

Answer 5

ONLY contains single bonds

Question 6

What does unsaturated mean?

Answer 6

contains AT LEAST one double bond between carbon atoms

Question 7

what is the general formula for Alkanes?

Answer 7

CnH2n + 2

Question 8

What is the general formula for Alkenes?

Answer 8

CnH2n

Question 9

Meth = how many carbon atoms?

Answer 9

1 carbon atom

Question 10

Eth = how many carbon atoms?

Answer 10

2 carbon atoms

Question 11

Prop = how many carbon atoms?

Answer 11

3 carbon atoms

Question 12

But = how many carbon atoms?

Answer 12

4 carbon atoms

Question 13

What is distillation?

Answer 13

separates components in a mixture that have different boiling points.

Question 14

What does volatile mean?

Answer 14

how easily it goes from liquids to gas.

Question 15

What is the homologous series?

Answer 15

Has the same functional group but each successive member differs by CH2

Question 16

what does “viscous” mean?

Answer 16

thick, does not flow easily

Question 17

suggest 3 reasons why bitumen is NOT used as a fuel

Answer 17

• not flammable
• highly viscous
• high boiling point

Question 18

why are larger hydrocarbon molecules in the diesel fraction oil cracked to produce smaller hydrocarbon molecules?

Answer 18

• more useful
• better fuels

Question 19

What is the test for alkenes?

Answer 19

bromine water (turns from orange to colourless)

Question 20

why do only alkenes decolourise bromine water?

Answer 20

alkenes have at least 1 double bond, which can open up, allowing addition reactions

Question 21

(cracking) long chain alkane is cracked into….

Answer 21

a shorter alkane + alkene

Question 22

what are the products for complete combustion?

Answer 22

carbon dioxide + water

Question 23

state the fractions produced by crude oil by fractional distillation (in order).

Answer 23

gases, gasoline (petrol), kerosene, diesel, fuel oil, bitumen

Question 24

what is kerosene used for?

Answer 24

aircraft fuel

Question 25

what is fuel oil used for?

Answer 25

ships, power stations

Question 26

what is bitumen used for?

Answer 26

roads and roofs

Question 27

in fractional distillation, the top part is _____ (cool/hot), and the bottom part is______ (cool/hot).

Answer 27

top part = cool (25 C)
bottom part = hot (350 C)

Question 28

how is crude oil separated into fractions and explain in terms of structure why the fractions can be separated in this way. (6 marks)

Answer 28

1. FRACTIONAL DISTILLATION carried out in fractioning column, hot on bottom, cool at top.
2. Crude oil enters the fractioning column and is HEATED so VAPOUR RISES.
3. Vapours of hydrocarbons with VERY HIGH BOILING POINTS will condense into liquid at higher temp. lower down and tapped off at bottom of the column.
   - Vapours of hydrocarbons with VERY LOW BOILING POINTS will rise up the column and condense at the top to be tapped off.
4. LONGER CHAINS have HIGHER boiling points/shorter chains have lower boiling points.
5. Longer chains have more intermolecular forces.
6. More intermolecular forces requires more energy (high temp.) to separate.

Question 29

what type of reaction is cracking?

Answer 29

thermal decomposition reaction

Question 30

what are the two ways of making ethanol?

Answer 30

1) fermentation
2) reacting ethene with steam

Question 31

what is the word equation for fermentation?

Answer 31

glucose –(yeast)—> ethanol + carbon dioxide

Question 32

what is the symbol equation for fermentation?

Answer 32

C2H12O6 —> 2 C2H5OH + 2 C02

Question 33

what is the word equation for reacting ethene with steam?

Answer 33

ethene + water –(phosphoric acid)–> ethanol

Question 34

what is the symbol equation for reacting ethene with steam?

Answer 34

C2H4 + H2O –> C2H5OH

Question 35

what are the advantages/disadvantages of the two processes of making ethanol?

Answer 35

fermentation steam
temp. 37 C 300 C

production 15% 96%
yield

sustainability renewable non renewable

process batch making continuous

purification fractional distillation during production

Question 36

write the word equation for complete combustion of ethanol.

Answer 36

ethanol + oxygen –> carbon dioxide + water

Question 37

write the symbol equation for complete combustion of ethanol.

Answer 37

C2H5OH + (3) O2 —> (2) CO2 + (3) H20

Question 38

describe how a condensation reaction happens.

Answer 38

• 2 monomers (with different functional groups) react.
• a condensation polymer and small molecule are made.

Question 39

Give 2 differences between addition polymerisation and condensation polymerisation.

Answer 39

Addition = 1 product, same monomer.
Condensation = 2 products, different monomers with different functional groups

Question 40

as you go down the crude oil fraction, what things increase? (3)

Answer 40

• chain length increases
• boiling point increases
• viscosity increases

Question 41

What type of reaction is ethene polymerising to form poly(ethene)?

Answer 41

addition reaction

Question 42

what are the conditions required for cracking?

Answer 42

1. high temperature
2. catalyst

Question 43

what are 3 conditions for fermentation?

Answer 43

1. using enzymes in yeast
2. temperature at 37 C
3. no oxygen (anaerobic)