17.7 The Alcohols Flashcards
What is their functional group?
OH
As the number of Carbon atoms increase, what happens to the boiling points?
Increases
What is their homologous series?
CnH2n+1OH
Why is ethanol called a good solvent?
Because it dissolves many substances that do not dissolve in water
What is the property that makes ethanol a food solvent for use in glues, printing inks, perfumes, and aftershave?
It is volatile
It evaporates easily.
Why is ethanol used as a fuel?
It burns readily in oxygen and gives out a lot of energy.
What is ethanol made of in the biological way , fermentation?
It is made of Glucose (a sugar)
And yeast
In the absence of air
(Anaerobic reaction)
Why is yeast used in fermination?
It contains enzymes that catalyse the reaction of termination
Is fermentation exo or endothermic?
Exothermic as it gives out energy with the alcohol and CO2 being produced.
What can break down into glucose, to be used in the reaction of fermentation?
Sugars, starch, Cellulose can break down to glucose so
Maize, sugarcane, potato and wood can make ethanol
When does the yeast stop working in the reaction of fermentation?
When the % of ethanol reaches a certain level or when the mixture gets to warm
How is the ethanol separated from the final mixture in fermentation?
By fractional distillation
What is the other way, other than fermentation, to produce ethanol?
By hydration ( chemical way) Adding water
Hydration to produce ethanol Is EthENE and water, what are the controls needed?
570 degree
60-70 atms pressure
Catalyst phosphoric acid
What type of reaction is the hydration of an AlkENE?
It is exothermic and reversible
High pressure and low temperature give the best yield in hydration of the AlkENE, Ethene. What is the temperature this reaction is carried out at?
570 degrees
What are the advantages of fermentation over hydration to obtain ethanol?
It uses renewable resources
You can use waste plant material
Disadvantage of fermentation?
A lot of plaint material is needed so a lot of land is needed.
Fermentation is slow, must start anew for each Batch.
Yeast stops to work at a certain % even if there is glucose left
You need heat for fractional distillation = money
Advantages of Hydration
Reaction is fast
Can be run continuously if the ethanol is removed whenever full
Give pure ethanol no need for fractional distillation
Disadvantages of hydration
Ethene is made form oil= not renewable resources which means it may run out
A lot of heat = money
Reversible reaction and 570 degrees doesn’t produce a high yield so the unreacted ethENE and steam.
What is the reaction of ethanol in oxygen?
C2H5OH + 3O2 -> 2CO2 + 3 H2O + heat (energy)
Why is ethanol used as a fuel more often now?
It is cheap
Many counties have no petroleum so it would be better to make ethanol than to imports petroleum
Can fight global warming, since many plants must be grown for ethanol to be produce although when it burns it also produces the greenhouse gas, CO2
