Which substance is heavier, chlorine or air?

Chlorine is heavier than air because its molecular weight is approximately 35.5 grams per mole, while the average molecular weight of air is around 29 grams per mole. This means that chlorine has a greater density compared to air, causing it to be classified as a heavier gas.

In practical applications, this property is significant, particularly in wastewater treatment and other industries where chlorine is used as a disinfectant. Knowing that chlorine is heavier than air can inform safety protocols, as it will tend to accumulate in lower areas, increasing the importance of proper ventilation and monitoring in spaces where chlorine gas may be present.

By contrast, substances like helium or nitrogen have molecular weights that are less than that of air. Helium, for example, is much lighter than air and is often used in balloons for that reason. Nitrogen, while also a component of air, has similar weight characteristics to air but does not outweigh it. Understanding these properties can help in evaluating and managing gases in various industrial processes, including wastewater treatment.