Chemistry CCEA AS Level 2.6 (Alcohols)

What is the general formula of an alcohol?

CnH2n+1OH

What is the functional group of an alcohol?

OH

Why are alcohols soluble in water?

They are able to form hydrogen bonds with water molecules

Why do alcohols have high boiling points?

Alcohols have hydrogen bonding between the separate molecules

Why does water solubility decrease down the homologous series?

The size of the (non-polar) alkyl group increases and the effect of the (polar) O-H group decreases

Why does boiling point increase down the homologous series?

Molecular size and mass both increase so there are stronger van der Waals forces between the molecules

What determines the classification of an alcohol?

The number of R groups attached to the carbon bonded to the OH group

How are alcohols prepared?

Refluxing the corresponding halogenoalkane with aqueous NaOH (in a hydrolysis reaction)

What do alcohols produce from combustion with excess oxygen?

CO2 and H2O

What do alcohols produce from combustion with limited oxygen?

CO, C and H2O

How is ethanol for fuel produced?

Fermentation of sugar (a renewable source) or hydration of ethene (a non-renewable source)

What do alcohols produce in a reaction with sodium?

The corresponding sodium alkoxide and hydrogen gas

What do alcohols produce in a reaction with HBr?

The corresponding bromoalkane

What do alcohols produce in a reaction with PCl5?

HCl gas and POCl3

What is a suitable oxidising agent for alcohols?

Acidified Potassium Dichromate(VI)

What do primary alcohols initially form when oxidised?

Aldehydes

What do primary alcohols form with further oxidation?

Carboxylic Acids

What do secondary alcohols form when oxidised?

ketones

What is the colour change observed when an alcohol is oxidised with acidified potassium dichromate(VI)?

Orange to Green