Question

In an experiment, two unknown compounds (one an ether and the other an amine) of equal molecular mass were dissolved in water. The result of the experiment is shown in the table.
Solubility Comparison
Unknown Compound Solubility (g/100 ml water)
A 4
B 0.25


Which of the following correctly explains the identity of Compound A and its solubility?
It is an amine; it contains a nitrogen atom that will allow nitrogen-hydrogen bonds to form while in water.
It is an ether; because the oxygen atom is within the carbon chain, so it is free to form oxy-hydrogen bonds to make it more soluble.
It is an ether; the high polarity of the oxygen-hydrogen bond makes it more soluble.
It is an amine; because the lower electronegativity of N than H makes it more soluble.

Answer 1

Answer:

It is an amine; it contains a nitrogen atom that will allow nitrogen-hydrogen bonds to form while in water.

Explanation:

The solubility of amines owes largely to the electronegativity difference between nitrogen and hydrogen. Remember that when hydrogen is bonded to highly electronegative element such as nitrogen, intermolecular hydrogen bonding is possible with water molecules. This explains the greater solubility of amines in water.

Ether molecules do have an oxygen atom, however, and engage in hydrogen bonding with water molecules to a lesser extent compared to amines.

Also, amines participate in some acid-base reactions that lead to the formation of diethylammonium hydroxide, an ion which leads to a greater solubility of amines compared to an ether.

Hence, compound A is an amine.