Would you expect H2O or H2S to be more volatile at the same temperature and pressure? Why?
You would expect the boiling point to be higher for H2O than for H2S because of hydrogen bonding in H2O. The problem didn't ask about boiling point, you say? Yes it did. It asks for volatility, that is vapor pressure, and that leads to boiling point.
To determine which compound, H2O (water) or H2S (hydrogen sulfide), is more volatile at the same temperature and pressure, we need to consider their molecular properties.
Volatility refers to a substance's tendency to vaporize or turn into a gas. The main factors affecting volatility are the strength and type of intermolecular forces between molecules.
In the case of H2O, it forms hydrogen bonds between water molecules. Hydrogen bonds are relatively strong intermolecular forces, which require large amounts of energy to break and convert water from a liquid into a gas. Therefore, H2O has a relatively low volatility compared to other compounds.
On the other hand, H2S does not form hydrogen bonds. Instead, it experiences weaker van der Waals forces between its molecules. Van der Waals forces are weaker than hydrogen bonds, making it easier for H2S to overcome these forces and evaporate into a gas at the same temperature and pressure.
Based on these intermolecular forces, we can expect H2S (hydrogen sulfide) to be more volatile than H2O (water) at the same temperature and pressure.