Question

Which of the following is the correct order of the solubility in water?
A.Propane $ < $ ethylamine $ < $ethyl alcohol
B.Propane $ < $ethyl alcohol $ < $ethyl amine
C.Ethyl alcohol $ < $propane $ < $ethylamine
D.Ethyl alcohol $ < $ethylamine $ < $propane

Answer 1

Hint:The solubility of substance depends on whether the substance is polar substance or nonpolar substance. Also the ability to form bonds with the substance also defines the amount of solubility in the water.

Complete step by step answer:
If we see the options there are 3 substances whose solubility in water is asked. Those are propane, ethylamine and ethyl alcohol. We will see each substance solubility in water.
First is propane: Propane is made of a saturated single bond that means$C{H_3} - C{H_2} - C{H_3}$. This is also known as non-polar hydrocarbon. So since it is non-polar hydrocarbon it doesn’t have free electrons to share with the water. Hence no electro-negativity in propane. Overall being non-polar, propane doesn’t dissolve in water.
Second is ethylamine: when it is added to water it has the tendency to interact with water. Hence when added to water it forms intermolecular hydrogen bonds with the water. And therefore ethylamine is soluble in water.
Last is ethyl alcohol: since as we know alcohols are highly soluble in water because of the presence of hydroxyl groups which result in formation of hydrogen bonds with water molecules. Also ethyl alcohol is polar in nature because of high electro-negativity of oxygen. Hence considering all facts it’s concluded that ethyl alcohol is highly soluble in water.
Hence if we see above explanations we can conclude that propane is least soluble in water. Amine and alcohol are both soluble in water but alcohol group has high solubility in water due to presence of hydroxyl group which makes higher tendency to make bonds with hydrogen in water.

Hence, option A is correct that is Propane $ < $ethylamine $ < $ethyl alcohol.

Additional Information:
The size of the molecule and functional group attached to the molecule determine the solubility of the substance in the water. Three or few carbon atoms will be more soluble in water. Those which are having six or more carbon will be insoluble.

Note:
Mostly the solubility of the substance depends on the size and the functional group attached to the molecule. The alcohol group is more soluble than the amine group whereas a molecule with no functional group is not soluble in the water.