Alcohols

OH hydroxyl

Primary Secondary or tertiary

Primary - this is when the carbon with OH group attached is attached to 1 carbon Secondary - this is when the carbon with OH group attached is attached to 2 other carbons Tertiary - this is when carbon with the OH group attached is attached to 3 other carbons

Dehydration reaction Elimination of water

CnH2n+1OH —> CnH2n + H2O

Hydration of alkenes

High temp (300•c) High pressure (70atm) Have to say concentrated Phosphoric acid catalyst or sulphuric acid

Fermentation of glucose Hydration of ethene with steam

Faster production Continuous process Virtually pure product

Ethene is non renewable - comes from crude oil fractions Crude oil will run out and ethene will be expensive And expensive initial costs

Exothermic

Addition of yeast Anaerobic conditions Temp of 35 degrees

C6H12O6 (aq) —-> 2C2H5OH (aq) + 2CO2 (g)

Yeast produces an enzyme which converts sugars such as glucose into ethanol and carbon dioxide

The enzyme works at this optimum temp If too cold the reaction is slow If too hot enzyme denatured damaged

It’s separated from the rest of the mixture by fractional distillation

It’s low tech Uses cheap equipment Uses renewable resources (sugar)

• The last fractional distillation step that’s needed to purify ethanol takes extra time and money • Batch process

Biofuel

A fuel that’s been made from biological material (plants) that’s recently died

Renewable energy resource - won’t run out so more sustainable They’re carbon neutral (they produce co2 when burnt however plants take in same amount of co2 during photosynthesis)

When switching from fossil fuel to biofuel in cars - they’re car engines would have to be modified to use fuels with high concentrations of ethanol Land used to grow crops for fuel cannot be used to grow food If countries use land to grow biofuel crops instead of food they may be unable to feed everyone in a country

So burning biofuel produces CO2, the same amount of CO2 is taken in by plants when growing so bio ethanol carbon neutral Plants take in carbon dioxide to produce glucose by photosynthesis….. 6CO2 + 6H2O —> C6H12O6 + 6O2 ….. 6 mol of co2 taken in from atomosphere to produce one mol of glucose In fermentation process, glucose converted to ethanol … C6H12O6 —> 2C2H5OH + 2CO2 … 2 mol of co2 rel into atmosphere when 1 mol of glucose converted to 2 mol of ethanol When Ethanol is burned CO2 and water are produced… 2C2H5OH + 6O2 —> 4CO2 + 6H2O … 4 mol of CO2 released when 2 mol of ethanol are burned completely So therefore If you combine all 3 equations exactly 6 mol of co2 are taken in and exactly 6 mol of co2 are given out

Fossil fuels will need to be burnt to power the machinery used to make fertilisers for crops, harvest the crops and refine and transport the bioethanol, this produces co2. So using bioethanol made by fermentation isn’t completely carbon neutral.