At room temperature, water is a liquid with a molar volume of 18 mL. At \(105^{\circ} \mathrm{C}\) and 1 atm pressure, water is a gas and has a molar volume of over 30 L. Explain the large difference in molar volumes.

The large difference in molar volumes between liquid and gaseous water, 18 mL and over 30 L respectively, can be attributed to the significant change in density (ρ) when water changes from the liquid to the gaseous state. In the liquid state, water molecules are close together and form hydrogen bonds, leading to a higher density. In the gaseous state, water molecules are far apart from each other, and hydrogen bonds are nearly absent, resulting in a lower density. As molar volume (V) is related to density through the formula \( V = \frac{M}{ρ} \), where M is the constant molar mass of water, the dramatic decrease in density when transitioning from liquid to gas leads to an increase in molar volume.