Alcohols Flashcards
What is the general formula of the alcohol homologous series?
CnH2n+1 OH
What is fermentation?
An exothermic process where glucose is converted to alcohol as a byproduct of anaerobic respiration in yeast.
Give the equation for the production of ethanol by fermentation.
C6H12O69(aq) –> 2C2H5OH(g) + 2CO2(g)
What are the conditions of the fermentation of alcohols?
Temperature = 35C Pressure = normal atmospheric pressure Catalyst = enzyme in yeast (zymase) Other = aqueous and anaerobic
What raw materials are used in the fermentation of alcohols and what are these types?
Carbohydrate crops (e.g. sugar, maize) They are renewable
Fermentation of alcohols - what is this type of process called?
Batch (stop-start)
What is the reaction rate of the fermentation of alcohols?
Slow.
What is the purity of alcohol in the fermentation of alcohols?
Impure (10%) (must be purified by fractional distillation which is costly)
What is the cost of fermentation of alcohols?
Expensive - cheap equipment needed, high labour costs.
What is the equation of combustion of ethanol?
C2H5OH + 3O2 + 3H2O
How is biofuel produced?
From renewable biological resources
Fermentation can occur at 25C. In industry the fermentation reaction is carried out at 35C rather than 25C
a) Suggest one advantage and one disadvantage for industry of carrying out the fermentation at this higher temperature.
Ethanol is produced as a faster rate
However, it is costly to keep the high temperature.
b) What does carbon neutral mean?
There is no net release of CO2 into the atmosphere.
Is fermentation carbon neutral?
It depends.
What happens in the hydration of ethene?
Ethene is mixed with steam and passed over a catalyst consisting of solid silicon coated with phosphoric acid.
What is the equation for the hydration of ethene?
CH2 = CH2 +H2O –> C2H5OH
What does hydration mean?
The addition of water to a compound.
What conditions are needed for the hydration of ethene?
Temperature = 300C Pressure = 70 atm Catalyst = concentrated phosphoric acid
What raw material are used for the hydration of ethene?
Crude oil
What raw material type used for the hydration of ethene?
Finite (non-renewable)
What type of process is the hydration of ethene?
Continuous
What is the reaction rate of the hydration of ethene?.
Fast
What is the purity of ethanol in the hydration of ethene?
Pure.
Describe the classification of alcohol
Primary, secondary and tertiary- according to how many other groups (R) are. Bonded to the carbon that has the -OH group.
Describe the physical properties of alcohols
The -OH group has hydrogen bonds between molecules which means also alcohols have higher melting points than alkanes of the same relative molecular mass.
What are elimination reactions?
Where the small molecule leaves the parent molecules. In alcohols it’s water so the elimination reaction of water is always dehydration
Describe the dehydration of alcohols.
Alcohols can be dehydrated with excess hot concentrated sulfuric acid or by passing the vapour over heated aluminium oxide. An alkene is formed.
