Scribd
Upload
690 views6 pages

IGCSE Chemistry: Alcohols Explained

This document discusses different topics related to alcohols in chemistry including: 1) Ethanol can be oxidized to ethanoic acid using potassium dichromate and sulfuric acid as a catalyst. 2) Ethanol can be produced through fermentation by yeast converting sugars like glucose into ethanol and carbon dioxide. 3) Ethanol can also be produced through the hydration of ethene using steam. Fermentation uses renewable resources but is slower, while hydration uses non-renewable resources but is more efficient.

Uploaded by

Abubakar Siddiq Ramin
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
690 views6 pages

IGCSE Chemistry: Alcohols Explained

This document discusses different topics related to alcohols in chemistry including: 1) Ethanol can be oxidized to ethanoic acid using potassium dichromate and sulfuric acid as a catalyst. 2) Ethanol can be produced through fermentation by yeast converting sugars like glucose into ethanol and carbon dioxide. 3) Ethanol can also be produced through the hydration of ethene using steam. Fermentation uses renewable resources but is slower, while hydration uses non-renewable resources but is more efficient.

Uploaded by

Abubakar Siddiq Ramin
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 6

CHEMISTRY IGCSE NOTES

Chapter – 26

Alcohol – All alcohols contain an OH group


covalently bonded to a carbon chain. The
most common alcohol is ethanol. Displayed
formulas of the members of the alcohol
group are shown below:
Oxidation of ethanol:
When you heat
ethanol with
potassium dichromate
under reflux in the
presence of dilute sulfuric acid which acts as
a catalyst, the dichromate acts as an
oxidising agent and oxidises ethanol to form
ethanoic acid. We observe that the orange
dichromate solution has turned green due to
the presence of Cr3+ ions.
Manufacture of ethanol by:

Fermentation – We will add yeast to a


sugar or starch solution and leave it in 30° –
40°C temperature for several days in the
absence of air. Enzymes in the yeast
(zymase) will convert the sugar into ethanol
and carbon dioxide.

The sucrose (sugar) is split into two smaller


sugars – glucose and fructose. Glucose and
fructose have the same molecular formula,
but different structures. They are isomers.
Enzymes in the yeast convert these sugars
into ethanol and carbon dioxide in a
multitude of small steps. Yeast is killed by
more than 15% of ethanol in the mixture, so
it is purified by fractional distillation.

C12H22O11 (aq) + H2O (l) → C6H12O6 (aq) + C6H12O6 (aq)

C6H12O6 (aq) → 2C2H5OH (aq) + 2CO2 (g)


Hydration of ethene – Ethanol is also made
by reacting ethene with steam, which is
called hydration. The process details are
included in the previous chapter.

C2H4 (g) + H2O (g) → C2H5OH (g)


Comparison between the methods of ethanol production:
Fermentation Hydration of ethene

Use of Uses Uses non-


resources renewable renewable
resources like resources like
sugar cane oil
Type of An inefficient An more
process batch process efficient
continuous
flow process
Rate of slow rapid
reaction
Quality of Produces very Produces
product impure much purer
ethanol that ethanol
requires
further
processing
Reaction Uses gentle Uses high
conditions temperature temperature
and ordinary and pressure
pressure
Dehydration of ethanol - Dehydration is
the removal of water from a compound. We
will soak a mineral wool in ethanol and
place it at the end of a test tube containing
hot aluminium oxide acting as a catalyst.
Ethanol vapour will pass over hot
aluminium oxide. Ethene will be collected
over water. Other alcohols too dehydrate in
a similar way.

C2H5OH (g) → C2H4 (g) + H2O (l)

You might also like