Question

Which of the following substances would you predict to have the highest ΔHvap?

Answer 1

Answer: Option (4) is the correct answer.

Explanation:

Heat of vaporization is defined as the heat energy which is necessarily added to a liquid substance in order to transform the quantity of the substance into a gas.

For example, in $H_{2}O$ there will be presence of strong hydrogen bonding and in order to break this bond high amount of heat energy is required.

Whereas $H_{2}$, $F_{2}$ and $SiF_{4}$ are all covalent compounds which are bonded together by Vander waal forces. As these forces are weak in nature hence, they require less amount of heat energy to convert into vapor state.

Hence, they have low value of $\Delta H_{vap}$. Also, Ar is a noble gas and it has only Vander waal forces. So, it will also have low value of $\Delta H_{vap}$.

Therefore, we can conclude that out of the given options $H_{2}O$ have the highest $\Delta H_{vap}$.