Question

Would air with water vapor be heavier or lighter than normal air without water vapor?


lighter


heavier

Answer 1

Air with water vapor is **lighter** than dry air without water vapor. This is because water vapor (H₂O) has a lower molecular weight (approximately 18 g/mol) compared to the average molecular weight of the other components of dry air, which is about 29 g/mol (largely composed of nitrogen and oxygen). When water vapor replaces some of the nitrogen and oxygen in the air, the overall density of the air decreases, making it lighter.