Boiling Points of Various Compounds

What is the correct order of increasing boiling points for the given compounds?

a) H₂O < N₂ < CS₂ < KCl

b) N₂ < H₂O < CS₂ < KCl

c) N₂ < KCl < CS₂ < H₂O

d) CS₂ < N₂ < KCl < H₂O

e) KCl < H₂O < CS₂ < N₂

Answer:

The correct order of increasing boiling points for the given compounds is H₂O < N₂ < CS₂ < KCl. Option b is the correct answer.

Water (H₂O) has the highest boiling point among the given compounds because it forms strong hydrogen bonds between its molecules. This bonding results in higher energy needed to break the bonds and transition to a gas phase, hence a higher boiling point.

Nitrogen (N₂) has the next lower boiling point compared to water because it is a nonpolar molecule with only weak van der Waals forces between its molecules. These forces are weaker than hydrogen bonds, leading to a lower boiling point.

Carbon disulfide (CS₂) has a slightly higher boiling point than nitrogen because it is a polar molecule with dipole-dipole interactions between its molecules. These interactions require more energy to overcome, resulting in a higher boiling point than nitrogen.

Potassium chloride (KCl) has the highest boiling point among the given compounds because it is an ionic compound. It has strong electrostatic attractions between its positively charged potassium ions and negatively charged chloride ions, requiring significant energy to break these interactions and vaporize the compound.

Therefore, the correct order of increasing boiling points for the given compounds is H₂O < N₂ < CS₂ < KCl, making option b the correct answer.