Alcohols 2 Flashcards
(9 cards)
What is the Balanced symbol equatin of Fermentation
C6H12O6 (aq)–> 2C2H5OH(aq) + 2CO2(g)
What are the conditions required for fermentation
- Yeast
- Anaerobic conditions -no oxygen- (because oxygen could cause extra reactions- it oxidises the ethanol produced to ethanoic acid (vinegar)
- Temp of 30-40 (38 is optimum temp)
What happens if the temperature is too high or too low in fermnetation
Too low: Reaction will be very slow
Too high:Yeast dies and enzymes denature
Advantages(3) and Disadvantages (3) of fermentation
Advantages :
* Sugar is a renewable resource
* Production uses low level technology
* Cheap equipment
Disadvantages:
* Batch process which is slow and gives high production costs
* Ethanol made is impure and needs purifying by fractional distillation
* Depletes land as crops need land
What is a biofule
A biofuel is a fuel produced from plants
Define carbon neutral
An activity that has no net annual carbon (greenhouse gas) emissions to the atmosphere”
Why is ethanol a biofuel
It can be argued that ethanol produced from this method is classed as carbon–neutral
Because any carbon dioxide given off when the biofuel is burnt would have been extracted from the air by photosynthesis when the plant grew.
There would be no net CO2 emission into the atmosphere.
Equations to show no net contribution to CO2
6 CO2 + 6 H2O –> C6H12O6 + 6 O2 -6 CO2 molecules are removed from the atmosphere when the plants grow by photosynthesis to produce one molecule of glucose.
C6H12O6 –> 2 CH3CH2OH + 2 CO2 -When 1 molecule of glucose is fermented 2 molecules of CO2 is emitted.
2 CH3CH2OH + 6O2 –> 4 CO2 + 6 H2O -The two ethanol molecules produced will then produce 4 molecules of CO2 when they are combusted.
Overall for every 6 molecules of CO2 absorbed, 6 molecules of CO2 are emitted. There is no net contribution of CO2 to the atmosphere.
Fact
Producing alkenes from alcohols provides a possible route to polymers without using monomers derived from oil
