Chapter 11, Problem 1DE

Interpretation Introduction

Interpretation:

The molecule that has a stronger force of attraction between ammonia and methylamine and the reasons for the same is to be determined. Also, based on the reasons, list the other experiment that is done with these molecules to test the same hypothesis is to be determined.

Conceptual introduction:

The force of attraction between the hydrogen and an electronegative atom is called hydrogen bonding.

The force of attraction between the same atoms of different molecules is called van der Waals force of attraction.

The force of attraction between the charged ion and a polar compound is called ionic-dipole interaction.

The force of attraction between the two polar compounds is called as dipole-dipole interaction.

To determine:

The molecule that has a stronger force of attraction from ammonia and methylamine and the reasons for the same.

Answer to Problem 1DE

Solution: The molecule that has a stronger force of attraction from ammonia and methylamine is methylamine and the reasons for the same are stated below.

Explanation of Solution

The force of attraction between the hydrogen and an electronegative atom is called hydrogen bonding.

Nitrogen is an electronegative atom compared to hydrogen. Therefore, there exist the hydrogen bonding interaction between the nitrogen of one ammonia molecule and the hydrogen of another ammonia molecule.

Thus, the liquification of ammonia gas is easier.

According to the given data, methylamine is liquefied more easily than ammonia, since, the boiling point of ammonia is less than that of methylamine.

Therefore, the interaction between the two methylamine molecules is stronger than that between two ammonia molecules.

The reason for this is that the interaction between the two methylamine molecules other than hydrogen bonding exist, that is, van der Waals forces. This is due to the hydrophobic regions of the two different molecules and the dipole-dipole interaction present between the carbon and the nitrogen atom in a molecule.

The solubility of a salt of methyl ammine is stronger than that of ammonia, since in methylammonium ion, the positive charge is stabilized by the positive inductive effect of the methyl group. This effect is absent in an ammonium ion.

The $\text{p}{K}_{\text{a}}$ of protonated ammonia and protonated methylamine is $9.26$ and $10.66$ , respectively.

Therefore, ammonia is less basic than methylamine. This is due to the inductive effect of methyl group that pushes electrons to extract a proton much easily. This effect is absent in ammonia.

Conclusion

Methylamine has stronger intermolecular force of attraction between its two molecule compared to that of ammonia.