True or False: H2S is heavier than air.

True or False: H2S is heavier than air.

• A. False
• B. It depends on conditions
• C. True
• D. Not sure

Answer: (C)

Gases with a higher molar mass than air are denser at the same temperature and pressure. Air has an average molar mass of about 29 g/mol, while H2S is about 34 g/mol. That extra mass makes H2S heavier than air, so it tends to settle in low-lying areas and can accumulate if ventilation is poor. Note that temperature and pressure can change density, but under normal conditions H2S is denser than air. So the statement is true.

Gases with a higher molar mass than air are denser at the same temperature and pressure. Air has an average molar mass of about 29 g/mol, while H2S is about 34 g/mol. That extra mass makes H2S heavier than air, so it tends to settle in low-lying areas and can accumulate if ventilation is poor. Note that temperature and pressure can change density, but under normal conditions H2S is denser than air. So the statement is true.