Alcohols - Physical Properties Flashcards
Do alcohols have a higher or lower boiling point than there corresponding alkanes?
They have a higher boiling point
What state are the first four members of the alkanes in?
They are cases
What state are the first four members of the alcohols in?
They are liquids
What are the higher boiling points of alcohols due to?
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They are due to the fact that the highly polar -OH group gives rise to hydrogen bonding between the alcohol molecules
Because of the hydrogen bonding, extra energy must be supplied to break these bonds
Therefore, alcohols have higher boiling points than the corresponding alkanes
No hydrogen bonds exist between the alkane molecules -only weak van der Waals forces
What alcohols are completely miscible in water?
Methanol, ethanol and propan-1-ol
Why is methanol, ethanol and propan-1-ol said to be infinitely soluble in water
As they are completely miscible with water ( miscible in all proportions)
What is the solubility of ethanol in water due to?
Hydrogen bonding between the alcohol molecules and the water molecules
How can 100% pure ethanol be formed?
By removing the water by a chemical drying agent such as calcium oxide which absorbs water
What is pure ethanol commonly called?
Absolute alcohol
What is 100% ethanol formed from?
95% ethanol
What is pure ethanol also called?
Absolute alcohol
What happens to the solubility of alcohols as the length of their carbon chains increase?
Their solubility decreases with the length of the carbon chain
Why does the solubility of alcohols decrease with the length of the carbon chain?
The tendency of the -OH group (polar) to make the alcohol soluble is counteracted by the insoluble alkyl (non-polar) portion of the molecule
Which alcohols are completely miscible in water?
The lower members of the series (C1-C3)
What can the long-chain alcohols dissolve in?
They can dissolve in solvents such as cyclohexane
