Alcohols
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Give two ways ethanol can be manufactured
Fermentation and hydration of Ethene
What occurs in fermentation
Glucose is fermented by yeast and turned into ethanol and carbon dioxide C6H12O6->2C2H5OH +2CO2
Give advantages and disadvantages of fermentation
Advantages Dosent require much energy Low tech process Renewable Disadvantage Slow process Produces mainly impure ethanol Batch process
What happens ins hydration of ethene and give the catalyst used and conditions involved
Water is added to ethene to make ethanol At 300 degrees 60 atmospheres H3Po4 catalyst
Give advantages of hydration and disadvantages
Advantages Relatively fast process Produces pure ethanol Continuous flow process Disadvantages Uses lots of energy Requires fairly high technology Non renewable
When is ethanol considered a biofuel
When it undergo fermentation and it’s carbon neutral
What 3 types of reactions can alcohols undergo
Elimination Nucleophillic substitution Oxidation
Give 3 types of alcohols
Primary alcohols-2 Hydrogens attached Secondary alcohols- 1 hydrogen attached Tertiary- no hydrogen
When is alcohols undergo Elimination what is it called and give the conditions involved and what is produced
It’s called dehydration 180 reflux conc sulphuric acid Alkenes
What is produced when a primary alcohol is oxidised
Aldehydes and water [O]
What is produced when an secondary alcohol is oxidised
A ketone and water
What is produced when a aldehyde is oxidised further and what else is needed for this too happen
Carboxylic acid is produced reflux 2[O]
What is the oxidising agent used in oxidation reactions with alcohols
Potassium dichromate in sulphuric acid
What colour change the oxidising agent undergo
It’s goes from orange to green
Give two tests used to distinguish between aldehydes and ketones
Feelings solution Tollens reagent
What happens when tollens reagent reacts with aldehydes or ketone
No reaction with ketone Ia sliver mirror forms when it reacts with aldehyde
What happens when fehlings solution react with a aldehyde or ketone
It reduces from blue to red when reacted with an aldehyde No reaction with ketone
Why is air kept out of fermentation vessels
To prevent oxidation of ethanol to ethanoic acid
State four essential conditions for fermentation of glucose
Yeast Absence of water Temperature of 30-40 Anaerobic conditions
State how you would distinguish between a primary alcohol and secondary alcohol/tertiary
Add potassium dichromate Primary alcohol will cause it to change from orange to green Secondary alcohol will result in no change
What is dehydration and state what is formed and the condtions needed for this reaction
It’s the removal of water from a compound and the condtions are conc H2SO4 at 180 Alkene
State how in an experiment a carboxylic acids form
We heat it the aldehyde under reflux
What is the mechanism for the formation of an Alkene from alcohol
Elimination conc H2SO4
What happens when a reaction mixture its refluxed
A mixture of liquids is heated to boiling point for a long time Vapours are formed which escape from the liquid mixture and return back It means any alcohol that initially evaporates is oxidised