Alcohols Flashcards
Why are alcohols soluble?
The polar OH- group forms hydrogen bonds with polar H2O molecules.
Which alcohols are soluble in water?
The first three members of the alcohol homologous series.
Does solubility of alcohols increase or decrease as the chain length increases?
Decreases.
Why does solubility of alcohols decrease down the homologous series?
- a larger part of the alcohol molecule is made up of a non-polar hydrocarbon chain
- the hydrocarbon chain does not form hydrogen bonds with the water molecules
Do alcohols have higher boiling points than alkanes?
Yes.
Why do alcohols have higher boiling points than alkanes?
- hydrogen bonds form between alcohol molecules
- a significant amount of energy is required to overcome the hydrogen bonds which requires more energy than breaking weaker London forces in alkanes so alcohols have a higher boiling point
What is a primary alcohol?
An alcohol where the OH- group is attached to a carbon with only one alkyl group.
What is a secondary alcohol?
An alcohol where the OH- group is attached to a carbon with two alkyl groups.
What is a tertiary alcohol?
An alcohol where the OH- group is attached to a carbon with three alkyl groups.
COMBUSTION OF ALCOHOLS
In plentiful supply of oxygen, alcohols…
completely burn to give carbon dioxide and water.
What is dehydration?
A reaction where one molecule is removed from a saturated molecule to form an unsaturated molecule.
What does the dehydration of ethanol produce?
Ethene and water.
What are the reagents/conditions needed for the elimination reaction of H2O from an alcohol?
- concentrated H3PO4/concentrated H2SO4, alcohol
- heat under reflux
Which alcohols can be oxidised?
Primary and secondary.
Which alcohols cannot be oxidised?
Tertiary.
