alcohols

What are alcohols?

Alcohols are a homologous series containing the functional group OH with the formula CnH2n+1OH

What are alcohols used for?

Used as solvents , fuels and ethanol is the alcohol present in alcoholic drinks

How can alcohols be formed?

Alcohols can be formed by direct hydration of ethene or fermentation of sugar

What happens when alcohols are dissolved in water?

Form a neutral solution

What happens when alcohol reacts with metals?

Alcohol reacts with metal to form ethoxides and hydrogen, effervescence of hydrogen

Two types of manufacture for alcohol

Fermentation and Direct Hydration

Differences between fermentation and direct hydration

Fermentation has:

• Renewable resources

• Solution of ethanol (15%)

• Slow (low temperature)

• Batch process

• Suitable for drinks manufacture

Direct Hydration has:

• Non-renewable resources

• Almost pure ethanol (100%)

• Fast (high temperature)

• Continuous process

• Suitable for use as fuel + in chemical industry

Importance of alcohols as fuels

• Methanol + Ethanol can both be used as fuels either as 100% fuels or blends (biofuels)

• The problem with petrol is its incomplete combustion + high levels of greenhouse gas emissions

• Combustion of alcohol fuels in a motor engine is more complete + produce no hydrocarbon emissions

Combustion of methanol

2CH3OH + 3O2 goes to 4H2O + 2CO2

Combustion of ethanol

CH3CH2OH + 3O2 goes to 3H2O + 2CO2