Alcohols Flashcards
What functional group do alcohols have?
OH - hydroxyl group
What is the use of methanol?
high performance fuel
What is the use of ethanol?
alcoholic drinks and as a fuel
solvents
How are alcohol properties different to alkane properties?
alcohols:
less volatile
higher MP
greater water solubility
Why do alcohols have a high MP?
have a polar OH bond - difference in electronegativity of O and H
molecule is therefore polar
weak lodon forces but much stronger H bonds between polar OH groups
What is the relationship of the chain length and BP in alcohols?
as the chain length increases, the contribution of the OH group decreases and the alcohol resembles the alkanes more closely
Why do alcohols have a lower volatility?
H bonds hold the alcohol molecules together in liquid state
require a lot of energy to break
What happens to the solubility of alcohols as the chain length increases?
as the chain lenbth increases in size, the influence of the OH group decreases and the solubility decreases
Is combustion of alcohols exothermic or endothermic?
exothermic
What is the oxidising agent of alcohols?
K2Cr2O7
What is the colour change of oxidising alcohols and what ions are present?
orange —-> green
dichromate ions (VI) —-> Chromium (III) ions
What acid is used in oxidising alcohols?
sulfuric acid
How is an aldehyde formed?
gentle heating of primary alcohols with acidifies potassium dichromate
What type of reaction is used to make an aldehyde?
distillation
How is a carboxylic acid fromed from an alcohol?
a primary alcohol is heated strongly under reflux with an excess of acified potassium dichromate (VI)
