Esterification, Gibbs Energy Flashcards
What is the name of the ester made up of?
The first part from the alcohol, the second part from the carboxylic acid
What is the functional group of an ester?
-COO-
How do you make an ester from an alcohol and carboxylic acid?
Heat a carboxylic acid with an alcohol in the presence of an acid catalyst, such as conc HCl
What is esterification?
A reaction in which you get an ester
How do you make ethyl ethanoate?
Reflux ethanoic acid with ethanol and conc sulfuric acid as a catalyst
As the reaction to produce an ester is reversible, what do you have to use to separate the product when its formed?
You have to use distillation
Why do you mix the ester product formed with sodium carbonate?
To react with any carboxylic acid that might of snuck in
What happens when the ester product is reacted with sodium carbonate?
The ethyl ethanoate forms a layer on top of the aqueous layer which can be easily separated using a separating funnel
What is ethyl ethanoate often used as?
A solvent in chromatography, and often has a pineapple flavouring
What is acid hydrolysis?
Where the ester is split into an acid and an alcohol
Why is the reaction between ethanoic acid and ethanol a condensation reaction?
A small molecule (water) is released
How do you perform acid hydrolysis?
Reflux ester with dilute HCl, which forms an alcohol and a carboxylic acid
What is base hydrolysis?
When you reflux the ester with a dilute alkali, such as dilute NaOH
What does base hydrolysis form?
A carboxylate ion and an alcohol
What do diols contain?
2 OH groups
What do dicarboxylic acids contain?
2 COOH groups
What do diols and dicarboxylic acids react to form?
Long esters chains, called polyesters
What is condensation polymersiation?
When dicarboxylic acids and diols react to form long ester chains (polyesters)
What is eliminated when dicarboxylic acids react with diols?
A water molecule
What are some properties of polyester fibres?
They are strong and flexible
What does delta G mean?
The free energy change
What does delta G equal?
Change in enthalpy - Temp X system entropy change
For a reaction to be feasible, what does delat G have to be?
Negative
In terms of equilibrium constants, what does delta G equal?
Delta G = -RT lnk
Why doesn’t a negative Gibbes energy change guarentee a reaction?
The reaction may have a very high activation energy2
