what is the pressure of oxygen gas that is collected over water at 25 degrees celcius at an atmostpheric pressure of 800 mmKg?

PO2 = 776.2 mmHg

Explanation:

When it comes to gases collected on water, Dalton's law is of the utmost importance:

Pgas = Patm - P*H2O

∴ P*H2O: vapor pressure

⇒ P*H2O (25°C) = 23.8 mmHg

∴ Patm = 800 mmHg

⇒ PO2 = 800 mmHg - 23.8 mmHg

⇒ PO2 = 776.2 mmHg