Chapter 15- Alcohols Flashcards
What is an alcohol?
Organic molecules with the functional group -OH
What is the general formula for alcohols?
CnH2n+1OH
What is hydration for alcohols and what are the conditions?
An industrial process that can be used to produce alcohols. The alkene is reacted with steam in the presence of an acid catalyst. Requires concentrated sulfuric acid under aqueous conditions at high temp. and pressure.
What are the pros and cons of making ethanol through cracking or hydration?
Fast, continuous, almost pure, high % yield (hydration)
Non-renewable
What is fermentation of glucose and what are the conditions required?
An industrial process to produce ethanol. Glucose is extracted from sugar cane. Yeast provides the enzymes needed for fermentation and then the glucose
produces ethanol and carbon dioxide. The reaction must be carried out anaerobically and at a warm temperature (30C).
What are the pros and cons of making ethanol through fermentation or distillation?
Renewable
Slow, batch, aqueous ethanol produced (impure)
What is ethanol produced from fermentation often used as?
A biofuel- a fuel derived from living matter
Why is the ethanol used as biofuel said to be carbon neutral?
The carbon dioxide given out in combustion (burning fuel) is said to be equal to the carbon dioxide taken in during the growth of crops. In reality, it is not, as transportation releases carbon dioxide.
What is a carbon-neutral fuel?
A fuel whose production and use has no net increase in the amount of carbon dioxide in the atmosphere
How are alcohols classed?
Alcohols can be primary, secondary or tertiary depending on the number of other R groups bonded to the carbon with the -OH group.
What does the oxidation of different alcohols produce?
1° alcohol –> aldehyde –> carboxylic acid
2° alcohol –> ketone
3° alcohols are not easily oxidised
What is used to oxidise alcohols, aldehydes and ketones and what is the observation?
Acidified potassium dichromate (VI) is the oxidising agent used. It turns from orange dichromate (VI) ions to green chromium (III) ions as they are reduced.
How is a 1° alcohol oxidised to make an aldehyde?
Mixture of alcohol and oxidising agent heated, oxidising the alcohol and forming an aldehyde which vaporises upon formation reducing further oxidisation.
How is a 1° alcohol oxidised to make a carboxylic acid?
Mixture of alcohol, excess acidified potassium dichromate (VI) is heated under reflux which causes vapour to condense and drip back into reaction flask. Produces a solution of ethanoic acid which can be distilled.
What is the equation for ethanol being oxidised to ethanal?
C2H5OH (l) + [O] –> C2H3O (g) + H2O (l)
