Help with Dalton’s law pls

Question

(Note: The pressure of Water at 20.0 degrees Celsius Is 17.5 torT)

Some hydrogen gas is collected over water al 20.0 degree calsius. The levels of water Inside and outside the bottle are the same. Partial pressure of Hydrogen is 742.5 Torr and Oxygen is 55.5 Torr. What is the barometric pressure at the time the gas is

collected?

Answer 1

Whenever a gas is collected over water, one must consider the vapor pressure of the water as part of the total pressure.

Total pressure = P_water + P_H2 + P_O2

Total pressure = 17.5 torr + 742.5 torr + 55.5 torr

Total pressure = 815.5