9.4 Alcohols and Carbolyxic Acids
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Functional group of alcohols
OH
General formula of alcohols
CnH2n+1OH
Name the first four alcohols
-Methanol -Ethanol -Propanol -Butanol
Methanol formula
CH3OH
Ethanol formula
C2H5OH
Propanol formula
C3H7OH
Butanol formula
C4H9OH
Why is methanol written as CH3OH and not CH4O?
It doesn’t show the functional group
How to make alkenes
Dehydrating alcohols
How to dehydrate alcohols into alkenes
Heat a mixture of an alcohol and an acid catalyst to form water and an alkene
Fermentation
The process of using yeast to convert sugars into alcohol
Word equation for fermentation
Sugar -> alcohol + carbon dioxide
Describe the process of fermentation
-Mix yeast and a solution of the carbohydrate in a container. Seal and leave in a warm place. -Keep the mixture in anaerobic conditions -When the concentration of alchohol is high enough, the yeast is killed off by the alcohol and will fall to the bottom of the container -Collect the alchohol solution from the top
How to concentrate the solution of alchohol
Distill it by fractional distillation
Why must the temperature be kept warm for fermentation
The enzymes in yeast work best at these temperatures
Why must fermentation be conducted in anaerobic conditions
Oxygen converts the alcohol into carbolyxic acid
Why can alcohols be used as fuels
They release energy when burned
Experiment to work out which alcohol is the best fuel
1- Put some alcohol into a spirit burner and measure the mass of the burner and fuel with a mass balance 2- Measure distilled water into a calorimeter, insulated with a drought excluder and an insulating lid 3- Take the initial temperature of the calorimeter then light the wick 4- Stir the water throughout using a thermometer. When the temperature of the water rises by a set interval blow out the spirit burner and reweigh the burner and fuel. 5- Repeat
Hazards of alcohol
-All flammable -Methanol is toxic -Propanol is an irritant
Control variables of the alcohol fuel experiment
-Mass/volume of water -Height of the container above the wick -Length of the wick -Number of moles of alcohol
What should the result of the alcohol fuel experiment be for a more efficient alcohol
If less fuel is used to raise the temperature
How does the length of the carbon chain relate to the efficiency of alcohols as fuels
Longer chains are more efficient fuels
How to make a carbolyxic acid
Oxidising an alcohol with an oxidising agent
How do solutions of carbolyxic acids behave
Like other acids