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AQA a level chemistry question

Hi,
Does anyone know why it is calcium sulfate? Of course with a drying agent in RP10, purification of an organic liquid you are going to need something that a)removes water but also b)doesn't react with the other compound in order for something to be an effective drying agent, but I cannot think of many reasons as to why the others would react? I know that hydroxides and carbonates may lead to the formation of white ppt with carboxylic acids, but what is the definitive difference?


A student is required to dry a liquid sample of pentanoic acid.


Which drying agent is suitable?



A

Calcium oxide



B

Calcium sulfate



C

Potassium hydroxide



D

Potassium carbonate
Original post by Notjustobsessed
Hi,
Does anyone know why it is calcium sulfate? Of course with a drying agent in RP10, purification of an organic liquid you are going to need something that a)removes water but also b)doesn't react with the other compound in order for something to be an effective drying agent, but I cannot think of many reasons as to why the others would react? I know that hydroxides and carbonates may lead to the formation of white ppt with carboxylic acids, but what is the definitive difference?


A student is required to dry a liquid sample of pentanoic acid.


Which drying agent is suitable?



A

Calcium oxide



B

Calcium sulfate



C

Potassium hydroxide



D

Potassium carbonate

All of the others react with carboxylic acids:
Calcium oxide is a base
Potassium hydroxide is a base
Potassium carbonate is a salt of a very, very weak acid (effectively it's a base also) ==> Salt + water + carbon dioxide
Original post by charco
All of the others react with carboxylic acids:
Calcium oxide is a base
Potassium hydroxide is a base
Potassium carbonate is a salt of a very, very weak acid (effectively it's a base also) ==> Salt + water + carbon dioxide

thank you :smile:

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