A 250 mL sample of oxygen is collected over water at 25 degrees Celcius and 760.0 torr pressure. What is the pressure of the dry gas alone?
It’s 736 torr
To find the pressure of the dry gas alone, we need to consider the vapor pressure of water at the given temperature of 25 degrees Celsius.
Step 1: Determine the vapor pressure of water at 25 degrees Celsius.
At 25 degrees Celsius, the vapor pressure of water is 23.8 torr.
Step 2: Calculate the pressure of the dry gas alone.
The total pressure obtained is the sum of the partial pressure of the dry gas and the vapor pressure of water. Mathematically, it can be represented as P_total = P_dry gas + P_water vapor.
P_total = 760.0 torr (given)
P_water vapor = 23.8 torr (vapor pressure of water at 25 degrees Celsius)
P_dry gas = P_total - P_water vapor
P_dry gas = 760.0 torr - 23.8 torr
P_dry gas = 736.2 torr
Therefore, the pressure of the dry gas alone is 736.2 torr.
You have to subtract the water vapor pressure at 25C from 760Torr.
http://intro.chem.okstate.edu/1515sp01/database/vpwater.html