Alcohol

Question 1

Conditions for the hydration of ethene by steam

Answer 1

300 degrees
60 atm
Phosphoric Acid Catalyst

Question 2

What is a renewable source for when ethene runs out?

Answer 2

Ethanol

Question 3

What is the chemical equation for ethanol from fermentation?

Answer 3

C6H12O6 –> 2C2H5OH + 2CO2

Question 4

Is fermentation endothermic or exothermic?

Answer 4

Exothermic

Question 5

What enzyme does fermentation of glucose require? What is the temperature optimum?

Answer 5

30-40 degrees
Yeast

Question 6

Does fermentation use anaerobic or aerobic conditions?

Answer 6

Anaerobic

Question 7

After forming, what happens to ethanol before use as a biofuel? Why?

Answer 7

Fractional distillation
To rid of the rest of impurities

Question 8

How can alcohols be produced other then fermentation?

Answer 8

By hydration of an alkene with an acid catalyst.

Question 9

Does hydration or fermentation have a higher percentage yield?

Answer 9

Hydration - produced only ethanol.
Fermentation - produces CO2 as well

Question 10

Is hydration or fermentation cheaper?

Answer 10

Fermentation
Required a lower temperature so cheaper tools

Question 11

Is hydration or fermentation slower?

Answer 11

Fermentation
Has to be made in batches whilst hydration can done industrially

Question 12

Is hydration or fermentation more renewable?

Answer 12

Fermentation
Uses renewable sources

Question 13

Is hydration or fermentation faster?

Answer 13

Hydration
Fermentations requires fractional distillation afterwards

Question 14

What is a biofuel?

Answer 14

A fuel made from from recently deceased biological molecules

Question 15

Why is biofuel good?

Answer 15

Renewable & Sustainable
Classified as carbon neutral

Question 16

Why is biofuel bad?

Answer 16

Petrol cars have to be modified to accommodate

Takes up land for growing crops for ethanol instead

Question 17

What are the equations showing biofuel as net zero?

Answer 17

Plants take in CO2:
6CO2 + 6H20 -> C6H12O6 + 6O2

Fermentation, glucose into ethanol:
C6H12O6 -> 2C2H5OH + 2CO2

Ethanol burnt and CO2 produced again:
2C2H5OH + 6O2 -> 4CO2 + 6H2O

Question 18

Why is the net zero classification not entirely accurate?

Answer 18

Make fertilisers for the crops
Harvest the crops
Refine the crops
Transport the crops

Question 19

What oxidant agent is used for alcohol? Chemical formula?

Answer 19

Potassium dichromate

K2Cr2O7

Question 20

Oxidation of a primary alcohol

Answer 20

Aldehyde -> Carboxylic acid

Question 21

Oxidation of a secondary alcohol

Answer 21

ketone

Question 22

Oxidation of a tertiary alcohol

Answer 22

No reaction

Question 23

How to collect an aldehyde before it oxides into carboxylic acid?

Answer 23

Distillation

Excess of alcohol

Question 24

How to collect carboxylic acid?

Answer 24

Reflux

Excess of oxidising agent

Question 25

Fehling solution on aldehyde vs ketone

Answer 25

Aldehyde Heated with water bath Can be oxidised -> Cu2+ to Cu+ -> Blue to red precipitate formed Ketone Heated with water bath Can not be oxidised -> No visible change

Question 26

Tollen's Reagent on aldehyde vs ketone

Answer 26

Aldehyde Heated with water bath Oxidised -> Carboxylic acid -> Reduces silver -> silver mirror Ketones Heated with water bath Can not be oxidised

Question 27

How do you make Tollen's reagent?

Answer 27

Add NaOH to silver nitrate Redissolve in ammonium hydroxide.

Question 28

Why does the mixture from dehydration need distilling?

Answer 28

Contains alkene (product), reactant, acid and water. Distilled for purity

Question 29

Needed example of distilling for a pure sample?

Answer 29

Cyclohexanol

Question 30

What happens in cyclohexanol: stage 1 - distillation?

Answer 30

1) Add concentrated sulphuric acid and phosphoric acid to a round bottom flask with cyclohexanol and anti-bumping granules 2) Gently heat mixture to 83 degrees using a heating mantle 3) Chemicals with a b.p under 83 degrees will evaporate and condense in the condenser 4) Product collected in cool flask

Question 31

Why is the cyclohexane mixture heated to 83 degrees?

Answer 31

As that is the boiling point of cyclohexane

Question 32

Why is a heating mantle used and not a Bunsen burner?

Answer 32

Cyclohexanol is highly flammable

Question 33

What happens in cyclohexanol: stage 2 - separation?

Answer 33

1) Transfer product containing impurities into a separating funnel and add water to dissolve water soluble impurities - create an aq solution. 2) Allow mixture to settle into layers. 3) Drain lower aqueous layer, leaving upper impure cyclohexane layer

Question 34

What happens in cyclohexanol: stage 3 - Purification?

Answer 34

1) Drain cyclohexane into a round bottom flask 2) Add anhydrous calcium chloride as a drying age and stopper the flask. 3) Allow mixture to dry for 20 minutes and invert 4) Distil one last time for impurities.

Question 35

Chemical test which can distinguish a carboxylic acid and aldehyde

Answer 35

Sodium carbonate Acid - Effervescence Aldehyde - No reaction

Question 36

What does anti bumping granules or small glass beads do?

Answer 36

Prevent bumping