Why is water a liquid at room temperature with a molar volume of 18mL and at 105 degrees C and 1 ATM pressure it is a gas with a molar volume of 30L?

Answer 1

the 30L water vapor sample is a gas

gases exert pressure on their surroundings thus taking on the shape of their containers

the gas is under 1 ATM of pressure so it exerts pressure in return and the volume becomes 30L when the presures are equal

if the temperature were to decrease to room temperature, the water vapor would condense to a liquid and the volume would decrease

liquids have a volume but no definite shape while gases have neither a definite volume or shape

Answer 2

At room temperature, water molecules have enough energy to overcome attractive forces and stay in a liquid state. When heated to 105 degrees C, the increased temperature causes water molecules to gain more kinetic energy, leading to increased intermolecular distances and resulting in water transitioning into a gas state with a higher molar volume. The difference in molar volume between the liquid and gas states of water at these temperatures is mainly due to the change in intermolecular distances and the expansion of the gas phase.