Alcohols
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What is the functional group of alcohols? What is this called?
-OH The hydroxyl group
What is the general formula for alcohols ?
Cn H2n+1 OH
How do you classify an alcohol?
By the number of carbons attached to the carbon carrying the OH
What is the equation for the fermentation of glucose?
(Yeast) C6H12O6 ———-> 2ethanol +2CO2
Give the conditions of the fermentation of ethanol
Yeast provides enzymes as a catalyst 35 degrees C so enzymes don’t denature Anaerobic respiration (oxygen free atmosphere)
What is the yield of ethanol from fermentation?
15%
What process is used to separate ethanol from the reaction mixture?
Fractional distillation
What are the conditions for the direct hydration of ethene?
Steam and concentrated H2SO4 or H3PO4
Give the details of a fermentation reaction
Rate: slow Quality of product: impure Raw material: sugar (renewable) Type of process: batch
Give details on the hydration of ethene
Rate: slow Quality: pure Raw material: ethene from oil (finite) Process: Continuous
Compare batch vs continuous processes
Batch: cheap equipment but expensive on manpower Continuous: cheap on manpower, expensive equipment
What is a biofuel?
A fuel produced from renewable biological resources
Define carbon neutral
An activity that has no net annual carbon emissions to the atmosphere
Why is fermentation considered carbon neutral?
Photosynthesis absorbs 6 moles of CO2 Fermentation releases 6 moles of CO2
Is fermentation actually carbon neutral?
No: CO2 is produced in other processes involved eg transport and harvest
Is ethanol a biofuel?
Yes it is used as motor fuel when mixed with petrol
Mechanism for an alcohol to an alkene Conditions??
Elimination Heated with concentrated H2SO4
What is the name of the reaction turning an alcohol to an alkene?
Dehydration Water is eliminated
What are the stages of an elimination reaction?
The alcohol oxygen’s lone pair is donated to a H+ provided by acid catalyst Oxygen gains H+ and a positive charge A hydrogen is lost from an adjacent carbon and the e- in the C-H bond move into the positively charged oxygen
What are the stages of separation for an impure organic liquid eg cyclohexene
Place impure organic liquid into a separating funnel and add a small amount (10cm3) of sodium hydrogen carbonate solution to eliminate XS acid catalyst Stopper separating funnel and shake Periodically invert and open tap to release pressure Allow funnel to stand and layers to separate Remove stopped and run off top and bottom layers into separate beakers Discard aqueous layer
Why must you periodically open the tap of the separating funnel?
To release a build up of pressure coming from the acid catalyst reaction with the sodium hydrogen carbonate, creating CO2
Once you have separated the organic liquid, there may be a little water left. What do you do now???
Add a spatula of drying agent (eg Calcium Chloride or MgSO4) to organic liquid Swirl and add drying agent until the liquid changes from cloudy to clear Filter to remove drying agent
List the equipment for distillation reaction
Round bottom flask Thermometer Condenser Heat
What is the distillate?
The product that evaporated and is condensed