Paper 2 Knowledge Gaps: Content

Question 1

How is ethanol produced?

Answer 1

Through fermentation

Question 2

How is ethanol concentrated?

Answer 2

fractional distillation

Question 3

Write a word equation for fermentation

Answer 3

Glucose –> ethanol + carbon dioxide

Question 4

What is the formula for ethanol?

Answer 4

C2H50H

Question 5

Where do the enzymes for fermentation come from?

Answer 5

From yeast cells

Question 6

State a quick overview of what happens in fermentation

Answer 6

Sugar or starch is dissolved in water and yeast is added

Question 7

What do the enzymes do in fermentation?

Answer 7

They break down the sugars to alcohol

Question 8

What does chemically oxidised alcohol produce?

Answer 8

Carboxylic acids

Question 9

Why must there be an air lock to ferment the ethanol?

Answer 9

To keep the oxygen out as yeast fermentation is a type of anaerobic respiration

Question 10

What is the highest concentration of alcohol produced by yeast fermentation?

Answer 10

15%

Question 11

Explain how fractional distillation is used to produce more concentrated solutions of alcohol such as ethanol

Answer 11

1. The water and ethanol solution are heated
2. Ethanol evaporates first as it has a lower boiling point than water, cools then condenses
3. The water left evaporates, cools then condenses

Question 12

Write a balanced equation for the formation of ethanol from carbohydrates

Answer 12

C6H12O6 + enzymes → 2CO2 + 2C2H5OH

Question 13

What is the general formula of a carboxylic acid?

Answer 13

Cn-1H2n+1COOH

Question 14

State the chemical properties of alcohol

Answer 14

• Produce carbon dioxide and water during complete combustion
• can be oxidised to form carboxylic acids
• react with reactive metals, forming water as one of the products

Question 15

Define addition polymerisation

Answer 15

A type of polymerisation in which the monomers add onto each other and no small molecule is eliminated. It only occurs with monomers that contain the double C bond

Question 16

How do ethene molecules join together to form poly(ethene)?

Answer 16

• They lose the carbon double bond
• which then transfers to the sides of each of the carbons
  to form a repeating unit

Question 17

How do we deduce the structure of a monomer from the polymer?

Answer 17

• Identify the repeating unit in the polymer
• Change the single bond in the repeat unit to a double bond in the monomer
• Remove the bond from each end of the repeat unit and the subscript n (which can be placed in front of the monomer)

Question 18

Define condensation polymerisation

Answer 18

A small molecule is formed as a byproduct each time a bond forms between two monomers

Question 19

What are the uses of poly(tetrafluoroethene)?

Answer 19

• nonstick coating for frying pans
• burette taps
• stain proof clothing

Question 20

What are the properties of poly(tetrafluoroethene)?

Answer 20

• tough
• slippery

Question 21

What are the uses of poly(chloroethene)?

Answer 21

• window frames
• gutters
• pipes

Question 22

What are the properties of poly(chloroethene)?

Answer 22

• tough
• good insulator
• rigid
• flexible

Question 23

What are the uses of poly(propene)?

Answer 23

• buckets
• food packaging
• ropes

Question 24

What are the uses of poly(ethene)?

Answer 24

• plastic bags and bottles
• cling film

Question 25

What are the properties of poly(propene)?

Answer 25

- flexible - shatterproof - strong

Question 26

What are the properties of poly (ethene)?

Answer 26

- flexible - cheap - good insulator

Question 27

What products are produced during the condensation reaction between an alcohol and a carboxylic acid?

Answer 27

Esters and water

Question 28

What particular position must the two monomers be whilst reacting under condensation polymerisation?

Answer 28

functional monomers must be facing each other so that the ester link can be formed between the carbon and oxygen and water can be removed

Question 29

What is the general formula of alcohol?

Answer 29

CnH2n+1OH.

Question 30

Describe how to carry out a hydroxide precipitate test

Answer 30

1. Place a little of the unknown solution in a test tube and add a few drops of dilute sodium hydroxide solution. Record any observations 2. If a white precipitate forms, add an excess of sodium hydroxide and record any observations

Question 31

What is the hydroxide precipitate test carried out for?

Answer 31

1. Place a little of the unknown solution in a test tube and add a few drops of dilute sodium hydroxide solution. Record any observations 2. If a white precipitate forms, add an excess of sodium hydroxide and record any observations

Question 32

What is the effect of adding sodium hydroxide to aluminium?

Answer 32

Forms a white precipitate, dissolves in excess NaOH to form a colourless solution

Question 33

What is the effect of adding sodium hydroxide to calcium?

Answer 33

White precipitate, insoluble, so remains in excess sodium hydroxide

Question 34

What is the effect of adding sodium hydroxide to copper?

Answer 34

Light blue precipitate, insoluble in excess

Question 35

What is the effect of adding sodium hydroxide to iron II?

Answer 35

Green precipitate, insoluble in excess

Question 36

What is the effect of adding sodium hydroxide to iron III?

Answer 36

Red-brown precipitate, insoluble in excess

Question 37

How can we test for **ammonium ions** using sodium hydroxide?

Answer 37

1. Gently heat the solution after adding the NaOH 2. If ammonium ion is present, it produces ammonium gas and can be tested with red litmus paper

Question 38

Describe the test for ammonia using HCl

Answer 38

1. React the gas with HCl 2. A white smoke is produced if ammonium gas is present of ammonium chloride

Question 39

How can we test for the presence of a carbonate ion?

Answer 39

Bubble the gas through limewater or any dilute acid. If the limwater goes cloudy, it indicates the presence of CO2

Question 40

How can we test for the presence of a sulfate ion?

Answer 40

1. Add dilute HCl followed by a barium chloride solution 2. A white precipitate of barium sulfate will form when sulfate ions are in the solution

Question 41

How can we test for the presence of halide ions?

Answer 41

1. Add dilute nitric acid followed by the addition of silver nitrate solution 2. This will form a silver halide precipitate 3. Depending on the halide present, a different colour precipitate is formed, allowing us to identify the halide ion

Question 42

What colour does chloride turn when added to a silver precipitate?

Answer 42

White

Question 43

What colour does bromide turn when added to a silver precipitate?

Answer 43

Cream

Question 44

What colour does iodine turn when added to a silver precipitate?

Answer 44

Yellow

Question 45

How is cataylitic cracking carried out?

Answer 45

- crude oil fractions are heated to evaporate them - vapours are passed over a catalyst containing aluminium oxides - this breaks the covalent bonds when they come into contact with the surface of the catalyst, causing thermal decomposition reactions - this produces a random selection of alkanes and alkenes

Question 46

How is steam/thermal cracking carried out?

Answer 46

- process carried out similar to catalytic cracking, but at higher temperatures - vapourised hydrocarbons are mixed with steam and heated to a high temperature, which induces cracking

Question 47

What is natural gas used for?

Answer 47

Domestic heating and cooking

Question 48

What is petrol used for?

Answer 48

Fuels for cars

Question 49

What is kerosene used for?

Answer 49

Jet fuel

Question 50

What is diesel used for?

Answer 50

Fuel for some cars and trains

Question 51

What is fuel oil used for?

Answer 51

Ships and power station

Question 52

What is bitumen used for?

Answer 52

Surfacing roads and roofs