Question

identify the principal type of solute - solvent interaction in a solution of ch₃nh₂ in ch₃oh. dipole - dipole interactions dispersion forces hydrogen bonding ion - dipole interactions identify the principal type of solute - solvent interaction in a solution of nbr₃ in h₂o. hydrogen bonding dipole - dipole interactions dispersion forces ion - dipole interactions

Explanation:

1. For $CH_3NH_2$ in $CH_3OH$: Both $CH_3NH_2$ and $CH_3OH$ have $N - H$ and $O - H$ bonds respectively. Hydrogen - bonding occurs when a hydrogen atom is bonded to a highly electronegative atom ($N$, $O$, or $F$) and is attracted to another electronegative atom in a neighboring molecule. So the principal interaction is hydrogen bonding.
2. For $NBr_3$ in $H_2O$: $NBr_3$ is a polar molecule (due to the lone pair on $N$ and the difference in electronegativity between $N$ and $Br$) and $H_2O$ is a polar molecule. But $NBr_3$ does not have $N - H$, $O - H$ or $F - H$ bonds for hydrogen - bonding with water. The polar - polar interaction between $NBr_3$ and $H_2O$ is a dipole - dipole interaction. However, $H_2O$ has hydrogen - bonding within its own molecules and the interaction between $NBr_3$ and $H_2O$ is mainly due to the ion - dipole interaction as $H_2O$ can act as a dipole and interact with the partial charges on $NBr_3$.

Answer:

1. C. hydrogen bonding
2. D. ion - dipole interactions