Answer:
[tex]P_{H_2}=727mmHg[/tex]
Explanation:
Hello there!
In this case, according to the given data, it is possible to infer that the gas mixture lies on the 15.0 cm-high column of water, so that the total pressure or atmospheric pressure is given by:
[tex]P_{atm}=P_{water}+P_{H_2}[/tex]
Thus, since the atmospheric pressure is 745 mmHg and the vapor pressure of water is 18 mmHg, the pressure of hydrogen turns out to be:
[tex]P_{H_2}=P_{atm}-P_{water}\\\\P_{H_2}=745mmHg-18mmHg\\\\P_{H_2}=727mmHg[/tex]
Best regards!