Question

A sample of hydrogen is collected by water displacement in the laboratory .The volume of the sample of hydrogen is 25 $mL$ at 24.0 ${}^{\circ }C$ and barometric pressure for the day of 758 $mmHg$. Find the pressure of the dry gas at this temperature ?

(The vapor pressure of water at 24.0 ${}^{\circ }C$ is 22.4 $mmHg$.)

• A. 455 $mmHg$
  
• B. 470 $mmHg$
• C. 736 $mmHg$
• D. 758 $mmHg$
• E. 780 $mmHg$

Answer 1

The correct option is C 736 $mmHg$

The pressure of the dry gas is obtained by subtracting the vapour pressure of water from the barometric pressure of the day.
It is $758-22.4=736mmHg$.