Slides in this set
· The general formula for alcohol is CnH2n+1OH.
· When naming an alcohol if there are more than one OH we use di-
, tri-, tetra-, ect...
· Alcohols can be classified as Primary (1o), Secondary (2o), or
· A primary alcohol has the OH group at the end of a chain. (IE the
main Carbon atom is attached to only one other Carbon atom).
· A secondary alcohol has the OH group in the body of the chain.
(IE The main Carbon atom is attached to two carbon atoms in the
middle of the chain).
· A tertiary alcohol has the OH group in the body of the chain and
attached to a branch.
· Alcohols have higher melting and boiling points because the
Oxygen molecule allows hydrogen bonds to form between the
· Alcohols are soluble in water because hydrogen bonds can form
between the OH groups and water molecules.…read more
· Alcohols are very useful in industry because they can be used as an
· They are easily made and easily converted into other compounds.
· EG Methanol can be used as a starting material for making other organic
· Ethanol is considered the most important alcohol.
· It is used as an intermediate in the manufacture of other organic
· It is often used as a solvent in cosmetics EG After shave, perfume.
· It is used in the manufacturing of drugs, detergents, inks and coatings.
· It is made by reacting ethene with steam using a catalyst: Phosphoric
· It can also be made from sugars by fermentation (Used to make
· Beers have 5% ethanol, wines have 12%. Spirits, such as gin and
whisky, contain 40% ethanol; these have been concentrated by
Ethene is produced when crude oil fractions are cracked. Alcohol
· The main sources is from ethane but some comes from the
· Ethene is hydrated, which means that water is added across the
· CH2=CH2 + H2O C2H5OH With a phosphoric acid
· During fermentation, carbohydrates from plants are broken down
into sugars, and then converted into ethanol by the action of
enzymes from yeast.
· The carbohydrates come from the crops such as sugar cane and
sugar beet. Starting material
Crude oil non- renewable Carbohydrates (sugars)
Method Cracking and dehydration Fermentation and distillation
Rate of reaction Fast Slow
Type of process Continuous batch
Purity Essentially pure Aqueous solution of ethanol
is produced…read more
The key steps in the break down of sugar in a process called
· Enzymes from yeast
C6H12O6 (aq) 2C2H5OH (aq) + 2CO2 (g)
· The rate of this chemical reaction is affected by temperature. It is
slow at low temperatures by the enzymes are made ineffective if
the temperature is too high. A compromise temperature of about
· Air is kept out of the fermentation vessels to provent oxidation of
ethanol to ethanoic acid (the acid in vinegar).
· Once the fermenting solution contains about 15% ethanol the
enzymes are unable to function and fermentation stops.
Carbon is useful as a motor fuel when
dioxide absorbed mixed
Carbon dioxide with petrol.
Photo synthesis in the growing plant Fermentation
6H2O (aq) + 6CO2 (g) C6H12O6 (aq) 2C2H5OH (aq) + 2CO2 (g)
C6H12O6 (aq) + 6O2 (g) 2C2H5OH (aq) + 6O2 (g) 4CO2 (g) + 6H2O (aq)
6 molecules of CO2 absorbed 6 molecules of CO2 released…read more
· Many conventional petrol engines will run on ethanol, or mixtures
of petrol and ethanol, with little modification, and much of the
petrol sold in the UK at present has 5 10% ethanol added.
· Ethanol made from ethene is not renewable fuel because it comes
from crude oil. However, ethanol made by fermentation is
renewable because the sugars come from plants such as sugar
cane and beet, which can be grown annually.
· Cars release Carbon dioxide into the atmosphere which is
associated with global warming and climate change.
· Ethanol made from fermentation is sometimes termed as carbon-
neutral fuel as it was obtained from photosynthesis.
· Ethene is a vital industrial chemical; it is the starting material for
poly(ethene) and many other important chemicals.
· We could produce ethene by dehydrating ethanol made from
sugar and this would give us renewable source of ethene.
· At present ethene is made from crude oil and then converted into
· In the future it may become more economical to make ethene
from ethanol made by fermentation.…read more
· C2H5OH (l) + 3O2 (g) 2CO2 (g) + 3H2O (l)
· Ethanol is often used as a fuel.
· Alcohols can also be oxidised gently and in stages.
· Primary alcohols are oxidised to aldehydes (R2CHO).
· Secondary alcohols are oxidised to Ketones (R2CO).
· Tertiary alcohols are not easily oxidised.
· This is because oxidation would need a C-C bond to break.
· Ketones do not oxidise further for the same reason.
· Many aldehydes and ketones have pleasant smells.
The experimental details
· A solution of potassium dichromate, acidified with dilute sulphuric
acid, is often used to oxidise alcohols to aldehydes and ketones.
· It is the oxidising agent.
· In the reaction, the orange dichromate (VI) ions are reduced to
green chromium (III) ions.…read more