Alcohols Flashcards
(20 cards)
What is the equation for the production of ethanol by fermentation?
C6H12O6 –> 2C2H5OH + 2CO2
What are the conditions required for ethanol produced by fermentation?
30 - 40°C
Presence of yeast
What are the advantages of the production of ethanol by fermentation?
- It uses renewable materials
- It takes place at a lower temperature and pressure (therefore decreasing cost)
What are the disadvantages of the production of ethanol by fermentation?
- Takes several days
- Is a batch process with higher labour costs
- Product is impure and needs to be distilled
What are the materials used to produce ethanol from fermentation?
Sugar cane, rice, sugar beet, corn, maize etc
What is the reaction for the production of ethanol from ethene with steam?
H2O + C2H4 <–> C2H5OH
Draw out the mechanism for the production of ethanol from ethene with steam
Well done
What are the conditions required for the production of ethanol from ethene with steam?
600K
60atm
Concentrated phosphoric acid catalyst
What are the advantages of producing ethanol from ethene with steam?
- Process is faster than fermentation
- Product is pure ethanol
- Is a continuous process with lower labour costs
What are the three equations that show that ethanol is a carbon neutral fuel?
6CO2 + 6H2O –> C6H12O6
C6H12O6 –> 2C2H5OH + 2CO2
2C2H5OH + 6O2 –> 4CO2 + 6H2O
So 6 moles of CO2 are taken in and 6 moles of CO2 are put out
What is produced when ethanol is oxidised?
Ethanal + water
What is produced when ethanal is oxidised?
Ethanoic acid
What is produced when ethanol is oxidised under reflux?
Ethanoic acid + water
What is produced when propan-2-ol is oxidised?
Propanone + water
Why can’t tertiary alcohols be oxidised?
Because the C-C and C-O bonds are too difficult to break
What are two oxidising agents?
Potassium dichromate (K2Cr2O7) and sulphuric acid (H2SO4)
What do Tollen’s and Fehling’s reagent test for?
They distinguish between aldehydes and ketones
Tollen’s - if a silver mirror forms then an aldehyde is present
Fehling’s - if a red precipitate is formed in the blue solution then an aldehyde is present
How do you test for the presence of an alkene / C=C bond?
Bromine water test
Positive colour change - orange –> clear solution
How do you test for a carboxylic acid?
Sodium carbonate
Positive result - bubbling as CO2 is formed (can also bubble the gas through lime water which will turn cloudy)
Draw out the mechanism for the reaction of propan-1-ol with concentrated sulphuric acid at a high temperature
What is this mechanism?
Well done
Dehydration of alcohol
