Question

The vapour pressure of water at $80{}^{\circ }C$ is 355 mm of Hg. A 100 ml vessel contains water saturated with $O_2$ at $80{}^{\circ }C$ the total pressure being 760 mm of Hg. The contents of the vessel were pumped into a 50 ml vessel at the same temperature, what is the partial pressure of $O_2$?

• A. 1115 mm
• B. 810 mm
• C. 405 mm
• D. 355 mm

Answer 1

The correct option is B 810 mm

Volume of $O_2$ = 100 ml
$p{O}_2=760-355=405$ mm
Since the temperature is constant,
Using Boyle's law we get,
$100\times 405=50\times p{O}_2$
$\Rightarrow p{O}_2=810$ mm