How to favour the forward reaction in an esterification reaction?

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canadahistorian
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As part of a Chemistry lab, I did an esterification reaction where I heated
ethanoic acid(aq) and octan-1-ol(1) in a hot water bath and using H2SO4(aq) as a catalyst, producing octylethanoate(l) and H2O(l). I added H2O(l) to produce the orange scent at the end.

I have to include in my write up what I did to favour the forward reactionso it does not undergo a hydrolysis reaction and revert back to the reactants. I'm not sure which part of the lab that would be? Should I say that since esterification is an exothermic reaction, heating it favoured the forward reaction and increased the rate of reaction? I thought it would be using the catalyst, but I believe that the cataylst can be used for the hydrolysis reaction too.

Thanks!
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LeChevalierMal
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Actually most esterifications are exothermic, think about all of those bonds you are forming!

You are heating it to provide activation energy, the way that you control the reaction is with drying agents like sulfuric acid in your case to remove water. This will remove one of the products shifting the equilibrium.
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canadahistorian
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(Original post by LeChevalierMal)
Actually most esterifications are exothermic, think about all of those bonds you are forming!

You are heating it to provide activation energy, the way that you control the reaction is with drying agents like sulfuric acid in your case to remove water. This will remove one of the products shifting the equilibrium.
Thank you for your response! Just to make sure I'm correct: the H2SO4 removes the H2O(l) produced in the reaction, preventing a hydrolysis reaction from taking place? I was using 3M H2SO4 if that makes a difference.
Last edited by canadahistorian; 1 year ago
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charco
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(Original post by canadahistorian)
Thank you for your response! Just to make sure I'm correct: the H2SO4 removes the H2O(l) produced in the reaction, preventing a hydrolysis reaction from taking place? I was using 3M H2SO4 if that makes a difference.
No, you would use concentrated sulfuric or phosphoric acid (both dehydrating agents) to pull the equilibrium to the right hand side...
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sivthasan
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(Original post by canadahistorian)
Thank you for your response! Just to make sure I'm correct: the H2SO4 removes the H2O(l) produced in the reaction, preventing a hydrolysis reaction from taking place? I was using 3M H2SO4 if that makes a difference.
When the alcohol and carboxylic acid react, water is produced alongside the ester.

Thinking about equilibrium, if you add a drying agent, this removes the H2O. The system will try to oppose the change through Le Chatelier's principle, and will favour the forward reaction to replace this water being removed.
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canadahistorian
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(Original post by charco)
No, you would use concentrated sulfuric or phosphoric acid (both dehydrating agents) to pull the equilibrium to the right hand side...
(Original post by sivthasan)
When the alcohol and carboxylic acid react, water is produced alongside the ester.

Thinking about equilibrium, if you add a drying agent, this removes the H2O. The system will try to oppose the change through Le Chatelier's principle, and will favour the forward reaction to replace this water being removed.
Thank you both for your responses! We haven't covered equilibrium of Le Chatlier's principle in class yet so that is probably why I am confused. I am a little unclear on what you mean when you say "The system will try to oppose the change through Le Chatelier's principle, and will favour the forward reaction to replace this water being removed.". The water being produced alongside the ester will be removed by the sulfuric acid as it is a drying agent, so more H2O will be produced by the alcohol and carboxylic acid, favouring the forward reaction?
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charco
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(Original post by canadahistorian)
Thank you both for your responses! We haven't covered equilibrium of Le Chatlier's principle in class yet so that is probably why I am confused. I am a little unclear on what you mean when you say "The system will try to oppose the change through Le Chatelier's principle, and will favour the forward reaction to replace this water being removed.". The water being produced alongside the ester will be removed by the sulfuric acid as it is a drying agent, so more H2O will be produced by the alcohol and carboxylic acid, favouring the forward reaction?
You really need to cover the equiibrium basics first before trying to understand the basis of Le Chatelier's principle.

Dynamic equilibrium:
rate forward = rate backwards
component concentrations are constant

A quotient is defined as [products]product coefficients/[reactants]reactant coefficients

At equilibrium the quotient is constant for any given temperature (it varies with temperature), this is called the equilibrium constant.

If any change to an equilibrium affects the value of the quotient, the system will respond so as to retore the value of the equilibrium constant.

In your example, removing the water from the equilibrium (by absorbing it with sulfuric acid) reduces the value of the numerator in the quotient. The system will respond by making more of the products until the quotient becomes equal to the equilibrium contant once again.
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