# Problem: A 2.00-L sample of O2(g) was collected over water at a total pressure of 785 torr and 25°C. When the O2(g) was dried (water vapor removed), the gas had a volume of 1.94 L at 25°C and 785 torr. Calculate the vapor pressure of water at 25°C.

###### FREE Expert Solution

$\overline{){{\mathbf{P}}}_{{\mathbf{H}}_{\mathbf{2}}\mathbf{O}}{\mathbf{=}}{{\mathbf{P}}}_{{\mathbf{total}}}{{\mathbf{X}}}_{{\mathbf{H}}_{\mathbf{2}}\mathbf{O}}}\phantom{\rule{0ex}{0ex}}{\mathbf{P}}_{{\mathbf{H}}_{\mathbf{2}}\mathbf{O}}\mathbf{=}{\mathbf{P}}_{\mathbf{total}}\frac{{\mathbf{mol}}_{{\mathbf{H}}_{\mathbf{2}}\mathbf{O}}}{{\mathbf{mol}}_{\mathbf{total}}}$

Step 1: Calculate the volume of water vapor

Since the pressure and temperature for the oxygen + water and oxygen only are the same, we can simply get the volume of water by subtracting.

80% (430 ratings) ###### Problem Details

A 2.00-L sample of O2(g) was collected over water at a total pressure of 785 torr and 25°C. When the O2(g) was dried (water vapor removed), the gas had a volume of 1.94 L at 25°C and 785 torr. Calculate the vapor pressure of water at 25°C.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Collecting Gas Over Water concept. If you need more Collecting Gas Over Water practice, you can also practice Collecting Gas Over Water practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Wink's class at UIC.

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition. You can also practice Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition practice problems.