Alcohols Flashcards
what is the bond angle of H-C-H bonds and C- C-O bonds and why
109.5 degrees
tetrahedral shape, 4 BP repelling to a position of minimum repulsion.
what is the bond angle of H-O- C
104.5 degrees
Bent line shape 2 bp and 2 lp
Lone pairs repel more than bonding pairs so the bond angle is reduced.
describe the Boiling point of alcohol
-alcohols have relatively low volatility and
high boiling points due to their ability to form hydrogen bond between alcohol molecules
define propan-1-ol Primary
Primary alcohols are alcohols where 1 carbon is attached to the carbon adjoining the oxygen.
define propan-2-ol Secondary
Secondary alcohols are alcohols
where 2 carbon are attached to
the carbon adjoining the oxygen.
define methylpropan-2-ol
Tertiary
Tertiary alcohols are alcohols
where 3 carbon are attached to
the carbon adjoining the oxygen
how are alcohols produced and state the conditions
Industrially by the hydration of alkenes in the presence of a catalyst
CH2=CH2 (g) + H2O (g) ➜CH3CH2OH (l)
Essential Conditions
high temperature 300 °C
high pressure 70 atm
strong acidic catalyst of conc H3PO4
how is ethanol produced
fermentation of glucose
What are the conditions for the fermentation of glucose and why are they used?
-Yeast
-No air
-temperatures 30 -40oC
-At lower temperatures the reaction is too slow.
-At higher temperatures the yeast dies and the enzymes denature.
-Fermentation is done in an absence of air because the presence of air can cause extra reactions to occur. It oxidises the ethanol produced to ethanoic acid (vinegar).
How is ethanol produced by fermentation separated and what can it be used as?
-By fractional distillation
-can be used as biofuel
What is a biofuel
a fuel produced from plants
advantages of fermentation
*sugar is a renewable resource
*production uses cheap equipment
disadvantages of fermentation
*batch process which is slow and gives high production costs
*ethanol made is not pure and needs purifying by fractional distillation
*depletes land used for growing food crops
advantages of using ethene
*faster reaction
*purer product *continuous process (which means cheaper manpower)
disdvantages of using ethene
*high technology equipment needed (expensive initial costs)
*ethene is non-renewable resource (will become
more expensive when raw materials run out)
*high energy costs for pumping to produce high pressures
discuss the environmental (including ethical) issues linked to decision making about biofuel use.
This does not take into account any energy needed to irrigate plants, fractionally distil the ethanol from the reaction mixture or process the fuel. If the energy for these processes comes from fossil fuels then the ethanol produced is not carbon neutral.
