Questions: A sample of nitrogen gas was collected via water displacement. Because the nitrogen was collected via water displacement, the sample is saturated with water vapor. If the total pressure of the mixture at 21°C is 1.227 bar, what is the partial pressure of nitrogen? The vapor pressure of water at 21°C is 18.7 mmHg. PN2= bar

Solution Steps

First, we need to convert the vapor pressure of water from mmHg to bar. The conversion factor is: \[ 1 \text{ bar} = 750.06 \text{ mmHg} \]

So, the vapor pressure of water in bar is: \[ P_{\text{H}_2\text{O}} = \frac{18.7 \text{ mmHg}}{750.06 \text{ mmHg/bar}} \approx 0.0249 \text{ bar} \]

The total pressure of the mixture is given as 1.227 bar. The partial pressure of nitrogen can be found by subtracting the vapor pressure of water from the total pressure: \[ P_{\text{N}_2} = P_{\text{total}} - P_{\text{H}_2\text{O}} \] \[ P_{\text{N}_2} = 1.227 \text{ bar} - 0.0249 \text{ bar} \] \[ P_{\text{N}_2} = 1.2021 \text{ bar} \]

Final Answer