ChemStream

Gas collection over water is a technique used to measure the volume of a gas by capturing it in an inverted container submerged in water. Since gases are less dense than liquids, they rise and displace water in the container, allowing for volume measurement.

Key Considerations:

1. Water Vapor Pressure:

   • When a gas is collected over water, it becomes saturated with water vapor.
   • The total pressure inside the container includes both the gas pressure and the water vapor pressure.
2.  Temperature Dependence:
   • The vapor pressure of water changes with temperature and must be accounted for when calculating gas pressure.

3. Applications:

   • Used in laboratory experiments to collect gases like oxygen, hydrogen, and carbon dioxide.
   • Common in gas law calculations (Boyle’s Law, Charles’ Law, Ideal Gas Law).