What is the partial pressure of oxygen collected over water if the temperature is 20.0°C and the total gas pressure is 735 mmHg?

Nov 22, 2015

$\text{718 mmHg}$

Explanation:

The trick here is to realize that the oxygen, which is collected over water, will be mixed with water vapor.

This means that the *total pressure8 of the mixture will have two components

• the partial pressure of oxygen
• the vapor pressure of water at ${20.0}^{\circ} \text{C}$

The vapor pressure of water at that temperature is approximately $\text{14.47 mmHg}$

http://www.endmemo.com/chem/vaporpressurewater.php

This means that you will have

${P}_{\text{total" = P_"oxygen" + P_"water}}$

P_"oxygen" = "735 mmHg" - "17.47 mmHg" = color(green)("718 mmHg")