Transcript alcohol - What is Chemistry?

Alcohols
Alcohols
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Methanol CH3OH
Ethanol
C2H5OH
Propan-1-ol C3H7OH
Propan-2-ol C3H7OH
Butan-1-ol
C4H9OH
Butan-2-ol
C4H9OH
Methanol CH3OH
Ethanol C2H5OH
Propan-1-ol C3H7OH
Butan-1-ol C4H9OH
Propan-2-ol CH3CH(OH)CH3
Butan-2-ol CH3CH(OH)C2H5
Classification of alcohols
1.
Primary alcohol: contains one carbon
atom directly attached to the carbon that
contains the hydroxyl group, e.g.
propan-1-ol
2. Secondary alcohol: contains two carbon
atoms directly attached to the carbon that
contains the hydroxyl group, e.g.
propan-2-ol
Physical properties
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Physical state: Liquid
Boiling points much higher than the
corresponding alkanes, due to polar OH
group
Physical properties
Solubility of methanol in
 (i) cyclohexane – not very soluble
methanol is polar cyclohexane is not
 (ii) water - completely soluble
because it is polar.
 As alcohol molecule gets bigger the polar
part becomes less significant so the alcohol
becomes less soluble in water and more
soluble in cyclohexane
Butan-1-ol is
– (i) soluble in cyclohexane
– (ii) not very soluble in water
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The polar OH group is becoming less
significant as the molecule gets bigger
Comparison with water
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Both have polar OH groups
Alcohols have a non-polar part
Both form hydrogen bonds between their
molecules
Water is more polar and has a greater
capacity to form hydrogen bonds and so has
a higher boiling point than methanol or
ethanol
Methanol
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Methanol: is toxic (can cause blindness, insanity and
death)
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It is added to industrial alcohol to prevent people
drinking it. This mixture is called methylated spirits.
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The methanol acts as a denaturing agent – it
renders a substance unfit for purpose without
destroying the usefulness or applications of the
substance. A purple dye is often added as a
warning.
Ethanol
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Ethanol: is produced by fermentation. Fruits provide
the sugar and yeast may need to be added.
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The enzyme zymase in yeast catalyses the reaction.
C6H12O6
2C2H5OH
+
2CO2
Alcoholic Drinks
Ingredient
Drink
Grapes
Wine
% (v/v)
alcohol
12
Apples
Cider
4.5
Malted
grain
Beer
5
Ethanol
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To produce drinks of higher alcohol
concentration the fermented liquids must be
distilled.
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Spirits (whiskey, brandy, gin, vodka) contain
40% alcohol.
Gasohol
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Ethanol obtained from sugar cane is used for
making gasohol in Brazil. This is then used
as a fuel.
Uses of ethanol
1.
Alcoholic drinks
2.
Fuel
3.
Solvent (can dissolve both polar and nonpolar solutes)