Alcohols Flashcards

1
Q

What conditions are required for the fermentation of ethanol?

A
  • yeast
  • absence of oxygen
  • 30-40°C
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2
Q

What are 2 ways can ethanol be produced?

A
  • fermentation
  • hydration of ethene
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3
Q

In what way is ethanol production considered carbon neutral?

A

There is no net production of carbon

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4
Q

What is formed when a primary alcohol is oxidised?

A
  • an aldehyde (distillation)
  • then further into a carboxylic acid (reflux)
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5
Q

What product is formed after oxidising a secondary alcohol?

A

a ketone

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6
Q

What type of reaction is the dehydration of alcohols?

A

an elimination reaction

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7
Q

What is a common oxidising agent for the oxidation of alcohols?

A

acidified potassium dichromate

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8
Q

Why can alcohols form hydrogen bonds? How does this impact their properties?

A
  • the O-H bond is polar due to the electronegativity of the oxygen atom
  • alcohols can form hydrogen bonds with each other and with water
  • this explains why they are soluble
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9
Q

Why are longer chain alcohols not soluble in water?

A

The longer chain length means the non-polar hydrocarbon chain dominates and therefore the effect of the H bond has little effect on the molecules properties

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10
Q

What does the term ‘volatility’ mean?

A

How easily something evaporates

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11
Q

Why might ethanol made by fermentation NOT be considered carbon neutral?

A

No transport or processing (of the crops) is taken into account, which have C emissions

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12
Q

Give the equations that can be used to argue that using ethanol as a fuel is carbon neutral

A

6CO2 + 6H2O –> 6O2 + C6H12O6
takes in 6CO2

C6H12O6 –> 2CO2 + 2C2H5OH
2 [C2H5OH –> 2CO2 + 3H2O]
in total 6 CO2 are released

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13
Q

What reaction can produce alcohols? (include reaction conditions in answer)

A
  • hydration,
  • (phosphoric) acid catalyst in aqueous conditions
  • high temperatures (300C) and pressures (60atm)
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14
Q

How is dehydration carried out?

A

excess of hot sulfuric acid and Al2O3 as a catalyst

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15
Q

How can H2SO4 be used to form an alcohol?

A

form an alkyl hydrogen sulfate (electrophilic addition), reacted with water (elimination) forms and alcohol

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16
Q

What does the dehydration of alcohols form?

A

alkene

17
Q

What colour change happens when alcohols are oxidised by potassium dichromate?

A

orange to green

18
Q

What side products does the dehydration of an alkene using H2SO4 produce?

A

CO2
SO2

19
Q
A