How much heavier is chlorine gas compared to air?

Chlorine gas is approximately 2.5 times heavier than air. This is based on the molecular weights of chlorine and the average molecular weight of air. The molecular weight of chlorine (Cl2) is about 70.9 g/mol, while the average molecular weight of air is roughly 29 g/mol. When you take the ratio of these two molecular weights, you find that chlorine gas is significantly denser than air, which explains why it will tend to sink in the atmosphere instead of rising.

This characteristic of chlorine is important in various applications, including its use in water treatment processes, as it can influence how the gas disperses in the environment and how it should be handled safely to avoid accumulation in lower areas. Understanding the relative density of chlorine gas facilitates proper safety protocols and effective operation in scenarios where chlorine is used.