Oxygen gas is collected over water at a temperature of 20c. If the totalmpressure of the system is 755mm, what is the pressure of the dry O2 gas?
vapor pressure H2O @ 20 C = ?. Look this up in tables in your text or notes. Call that pH2O
Then Ptotal = pH2O + pO2.
You know Ptotal and pH2O, solve for pO2.
To find the pressure of the dry O2 gas, we need to determine the partial pressure of water vapor in the system and subtract it from the total pressure.
Here's how you can calculate it step by step:
Step 1: Look up the vapor pressure of water at the given temperature. At 20°C, the vapor pressure of water is approximately 17.5 mmHg.
Step 2: Convert the temperature of 20°C to Kelvin. To convert Celsius to Kelvin, add 273 to the temperature. So, 20°C + 273 = 293K.
Step 3: Subtract the vapor pressure of water from the total pressure to get the pressure of the dry O2 gas.
Dry O2 pressure = Total pressure - Water vapor pressure
= 755 mmHg - 17.5 mmHg
= 737.5 mmHg.
Therefore, the pressure of the dry O2 gas is approximately 737.5 mmHg.