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?
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
The vapor pressure of water at that temperature is approximately
This means that you will have
#P_"total" = P_"oxygen" + P_"water"#
#P_"oxygen" = "735 mmHg" - "17.47 mmHg" = color(green)("718 mmHg")#