when 1 gram of water evaporated the volume of the water vapor increases but the mass remains constant.
why does the water remain constant
i think because the number of atoms remain constant
The reason the mass of water remains constant when it evaporates is because the number of water molecules or atoms does not change during the process of evaporation. Evaporation occurs when the kinetic energy of water molecules increases to the point where they can break free from the liquid and form a gas or vapor.
To understand why the mass stays constant during evaporation, you can think about the conservation of mass principle, which states that mass is neither created nor destroyed in a closed system. In this case, the closed system is the container holding the water.
As water molecules gain energy and move faster, some of them at the surface of the liquid have enough energy to escape into the air, becoming water vapor. However, the vapor that escapes still contains the same number of water molecules as the liquid water, just with increased spacing between them.
This means that while the water is transitioning from liquid to vapor, the total mass of the water (including both liquid and vapor phases) remains constant. The mass of the water vapor is simply spread out over a larger volume due to the increased spacing between the water molecules.
So, to summarize, during evaporation, the mass of water remains constant because the number of water molecules or atoms does not change. The water molecules gain enough energy to transition into the gas phase, forming water vapor, but the total mass remains the same.