Question

A 5 grams sample of liquid water evaporates into gaseous water in a closed container, expanding in the process. What is the mass after evaporation?

Answer 1

We have get the mass of gaseous water after evaporation in a closed container.

The mass of water vapor after evaporation is 5 grams.

In closed container, there is no exchange in mass from system to surrounding, only heat may exchange. The number of moles of water vapour remains unchanged as 5 gram water is heated in closed container.

Due to heating, liquid water gets evaporated and intermolecular distance between water molecules increases in gaseous state than liquid state and intermolecuar force of attraction decreases.

Randomness of  molecules increases in gaseous state than liquid state.