Alcohols and carboxylic acids (Section 6) Flashcards
What is the general formula for alcohols?
CnH(2n+1)OH
What is the functional group for alcohols?
-OH
What do alcohols form when oxidised?
Carboxylic acids
Name an oxidising agent that can be used to oxidise an alcohol to form a carboxylic acid
Potassium dichromate(VI) (In dilute sulfuric acid)
State the colour change when an alcohol is oxidised
The potassium dichromate (VI) solution will go from orange to green
What is formed after ethanol is oxidised?
Ethanoic acid
What are the products of complete combustion?
Carbon dioxide and water
What are the two ways to produce ethanol?
Fermentation and direct hydration (Ethene and steam)
How is ethanol created from direct hydration (Ethene and steam)
.Ethene is produced from the cracking of crude oil
.Ethene (C2H4) will react with steam (H2O)to make ethanol (C2H5OH)
.The reaction needs to happen at 300 degrees C and a pressure of 60-70 atmosphere
.Phosphoric acid is used as a catalyst
What is the catalyst used in Direct hydration?
Phosphoric acid
What temperature should direct hydration take place at
300 degrees celcius
what pressure should direct hydration take place at?
60-70 atmosphere
What are the advantages of direct hydration?
.Cheap at the moment
.No waste products
.100% yeald
.Fast
What are the disadvantages of direct hydration?
.Crude oil is non renewable which means it will start to run out soon
.Ethene will eventually become expensive
How is ethanol created using fermentation?
-Sugar (glucose) is converted into ethanol using yeast
-Yeast cells contain an enzyme which is a biological catalyst
-The mixture needs to be at 30 degrees C
-If it’s too hot the enzymes denature and if it’s too cold the reaction will be too slow
-It is important to ensure the mixture is kept in anaerobic conditions otherwise the the oxygen will convert the ethanol into ethanoic acid
What are the advantages of fermentation?
.Yeast is easy to grow
.The raw materials are renewable resources
.Cheap and low energy cost
What are the disadvantages of fermentation?
.The ethanol isn’t very concentrated
.Needs to be distilled and purified
.Slow
Why does fermentation take place at 30 degrees C?
.30 degrees C is the optimum temperature for the enzymes in yeast cells
.If it’s too hot, they denature
.If it’s too cold, the process would be to slow
What are the products of fermentation?
Ethanol and carbon dioxide
Why is ethanol purified and distilled after fermentation?
As it isn’t concentrated enough after fermentation
What is the functional group of carboxylic acids?
-COOH
What is the molecular formula of methanoic acid?
HCOOH
Do carboxylic contain double bonds?
Yes, on the carbon to the oxygen
What are the products of Ethanoic acid + sodium carbonate?
Sodium ethanoate + water + carbon dioxide
What are the products of Ethanoic acid + magnesium?
Magnesium ethanoate + hydrogen
How are esters formed?
When an alcohol is reacted with a carboxylic acid with the presence of an acid catalyst
How can ethanoic acid be made?
By oxidising ethanol
What are the products of ethanol + oxygen?
Ethanoic acid + water
How would you make vinegar?
.By oxidising ethanol to make ethanoic acid
.Then you can dissolve the ethanoic acid in water to make vinegar
What is vinegar used for?
Flavoring and preserving foods
