Organic Chemistry - Module 2 Flashcards
Which two chemical processes can be used to make ethanol?
The hydration of ethene and the fermentation of sugars.
Which catalyst is used for the hydration of ethene?
Phosphoric acid - H3PO4
When hydrating ethene, why is only 5% of the ethene converted into ethanol?
It is a reversible reaction.
In fermentation, carbohydrates are converted into which two products?
Ethanol and carbon dioxide.
Which two things are usually used as the carbohydrate source in fermentation?
Sugar or starch.
Why is yeast used during fermentation?
It contains an enzyme called zymase which catalyses the reaction.
Why can’t fermentation take place at temperatures above 37 degrees?
The enzyme in the yeast begins to denature and lose efficiency.
Why does the toxicity of the alcohol limit the concentration of ethanol that can be made?
The enzyme in the yeast ceases to function above an alcohol concentration of 14%.
Why does fermentation need to take place in the absence of air?
It prevents ethanol being oxidised into undesirable compounds like ethanal or ethanoic acid, which would affect the flavour.
Why do alcohols have higher boiling points than alkanes?
Because of the presence of hydrogen bonds in alcohols, which are strong.
Why do alcohols dissolve in water?
Because hydrogen bonds form between the O-H groups of the alcohols and the water molecules, because both of them are polar.
Define a primary alcohol.
When the O-H group of the alcohol is only attached to a carbon atom with no alkyl groups or is attached to one alkyl group.
Define a secondary alcohol.
When the O-H group of the alcohol is attached to two alkyl groups.
Define a tertiary alchol.
When the O-H group of the alchol is attached to three alkyl groups.
Which products are formed when alcohols burn completely?
Carbon dioxide and water.
