4. Alcohols
No description yet. This curated deck is ready for daily study.
Card preview (16)
What functional group do alcohols contain? Ethanol Example I
It is responsible for their characteristic reactions
Molecular, Displayed and Structural Formula for Methanol
CH3OH CH3OH
Molecular, Displayed and Structural Formula for Ethanol
C2H5OH CH3CH2OH
Molecular, Displayed and Structural Formula for Propan-1-ol (propanol)
C3H7OH CH3CH2CH2OH
Molecular, Displayed and Structural Formula for Butan-1-ol (Butanol)
C4H9OH CH3CH2CH2CH2OH
State the three ways that ethanol can be oxidised.
• Burning in air or oxygen (complete combustion) • Reaction with oxygen in the air to form ethanoic acid (microbial oxidation) • Heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid
How can ethanol be oxidised by burning in air or oxygen?
Ethanol undergoes complete combustion to form carbon dioxide and water. ethanol + oxygen → carbon dioxide + water
How can ethanol be oxidised by reaction with oxygen in the air?
Bacteria in the air use oxygen to oxidise ethanol into ethanoic acid — this is microbial oxidation. ethanol + oxygen → ethanoic acid + water
How can ethanol be oxidised using potassium dichromate(VI)?
When ethanol is heated with potassium dichromate(VI) (K2 Cr2 O7) in dilute sulfuric acid, it is oxidised to ethanoic acid. ethanol + oxygen [O] → ethanoic acid + water Turns from orange to green!
State the two ways ethanol can be manufactured.
• Reacting ethene with steam • The fermentation of glucose
What conditions are required to manufature ethanol by reacting ethene with steam.
• The presence of a phosphoric acid catalyst • A temperature of about 300 ºC • A pressure of about 60–70 atm ethene + steam → ethanol
What conditions are required to manufature ethanol by the fermentation of glucose.
• The absence of air • An optimum temperature of about 30 ºC • Using the enzymes in yeast C6H12O6 → 2CO2 + 2C2H5OH
Explain why the absence of air is required for the fermentation of glucose to produce ethanol.
In the presence of air (aerobic conditions), enzymes in the yeast produce carbon dioxide and water instead of ethanol.
Explain why an optimum temperature of about 30 ºC is required for the fermentation of glucose to produce ethanol.
• If the temperature is too low the reaction rate will be too slow • If it is too high the enzymes will become denatured
Discuss the advantages of fermentation/disadvantages of hydration for the production of ethanol.
• Sugar cane can be re-grown/is renewable • Crude oil is finite / is non renewable • Fermentation uses lower temperatures so energy costs are lower/ hydration uses higher temperatures, so energy costs are higher • Fermentation uses lower pressure so energy costs are lower/ hydration uses higher pressure, so energy costs are higher • Yeast is a natural substance and not harmful/ phosphoric acid is corrosive
Discuss the advantages of hydration/disadvantages of fermentation for the production of ethanol.
• Hydration is a faster process/ fermentation is a slower process • Hydration gives pure ethanol/ fermentation gives impure ethanol • Growing sugar cane takes up land which could be used for growing food/rearing livestock • Hydration is a continuous process/fermentation is a batch process