Question

Arrange these compounds by their expected vapor pressure: H2O NCl3 Br2

Answer 1

Answer: Given compounds are arranged in decreasing order of their vapor pressure as follows.

        $Br_{2}$ > $NCl_{3}$ > $H_{2}O$

Explanation:

Vapor pressure is defined as the pressure exerted by the vapors which are present on the surface of a liquid. Less is the intermoecular forces present within the molecules of a substance more will be its vapor pressure.

For example, $Br_{2}$ is a gas and there exists Vander waal forces between its molecules. Hence, it has more vapor pressure than $NCl_{3}$ and $H_{2}O$.

In $H_{2}O$, there exists hydrogen bonding which is stronger than bonding present in $NCl_{3}$. So, $H_{2}O$ has low vapor pressure.

In $NCl_{3}$, there exists dipole-dipole interaction which is stronger than Vander waal forces but weaker than hydrogen bonding.

Therefore, given compounds are arranged in decreasing order of their vapor pressure as follows.

        $Br_{2}$ > $NCl_{3}$ > $H_{2}O$