Final answer:
The pressure of the H₂ gas collected over water is 740.3 torr, calculated by subtracting the vapor pressure of water (19.7 torr) from the total pressure in the eudiometer (760.0 torr).
Step-by-step explanation:
To calculate the pressure of the H₂ gas collected over water in a eudiometer, we use the principle that the total pressure is the sum of the partial pressures of the gases present. In this case, the total pressure in the eudiometer is 760.0 torr, which includes both the partial pressure of the hydrogen gas and the vapor pressure of water. The vapor pressure of water under the given experimental conditions is 19.7 torr. Therefore, the pressure of the H₂ gas can be found by subtracting the vapor pressure of water from the total pressure.
Pressure of H₂ = total pressure - vapor pressure of water
Pressure of H₂ = 760.0 torr - 19.7 torr
Pressure of H₂ = 740.3 torr
The pressure of the H₂ gas collected over water is 740.3 torr.