# Finding partial pressure with only T, V and ambient P

• Felchi
In summary, the question is asking for the partial pressure of nitrogen in a mixture of gases collected over water at 40oC and atmospheric pressure of 760 torr. The ideal gas law is not applicable as the water vapor pressure and total pressure are known, and the total pressure cannot be assumed to be ambient pressure. Instead, the partial pressure of nitrogen can be calculated by subtracting the equilibrium vapor pressure of water at 40oC (7.3590 KPa) from the total pressure (101.3 kPa), resulting in a partial pressure of nitrogen of 93.941 kPa. The given volume of 60 L and the mass of water are not needed to solve this problem.
Felchi

## Homework Statement

60 L of N2 are collected over H2O at 40oC when atmospheric pressure is 760.00 torr. What is partial pressure of N2?

## Homework Equations

PV=nRT
Pt=P1+P2...

Vapor pressure of H2O at 40oC:7.3590 KPa
760 torr=101.3 kPa
40oC=313oK

## The Attempt at a Solution

PV-nRT
(60)101.3=313(n)8.3145
((60)101.3)/((313)8.3145)=2.166g...That doesn't help, mass of H2O unknown.

Pt=P1+P2?

Pt=101.3kPa+PN...Pt is not given...doesn't work.

Cannot assume Pt is ambient pressure because container's height affects pressure.

This has nothing to do with the ideal gas law. That's just a "red herring" that they threw into confuse you. The nitrogen has been bubbled through water, so the bubbles have come to the equilibrium vapor pressure of water at the temperature of the liquid. If the partial pressure of the water is its equilibrium vapor pressure and the total pressure is 760 mm Hg, what is the partial pressure of the nitrogen?

Chet

And the 60L seems also thrown into confuse you - second question with that feature in a row.

Chestermiller
Let's face it - in the real world we are distracted by so many things, it is quite a good idea to add unnecessary information to problems just to make students learn what and when to ignore ;)

## 1. What is partial pressure?

Partial pressure is the pressure exerted by a single gas component in a mixture of gases. It is equal to the total pressure multiplied by the mole fraction of that gas component.

## 2. How do you calculate partial pressure?

To calculate the partial pressure of a gas component, you need to know the total pressure of the gas mixture, the mole fraction of the gas component, and the total volume of the gas mixture. You can then use the formula P = PTOTAL * X, where P is the partial pressure, PTOTAL is the total pressure, and X is the mole fraction of the gas component.

## 3. Can you find partial pressure with only temperature, volume, and ambient pressure?

Yes, you can find partial pressure with only temperature, volume, and ambient pressure. As long as you know the total pressure and the mole fraction of the gas component, you can use the formula P = PTOTAL * X to calculate the partial pressure.

## 4. What are some applications of finding partial pressure?

Finding partial pressure is important in many scientific fields, such as chemistry, physics, and biology. It is used in gas law calculations, gas phase reactions, and gas exchange in the lungs. It also has practical applications in industries such as chemical manufacturing and gas storage.

## 5. Can you find the partial pressure of a gas without knowing its mole fraction?

No, you cannot find the partial pressure of a gas without knowing its mole fraction. The mole fraction is a crucial component in the formula for calculating partial pressure, so it is necessary to have this information in order to accurately determine the partial pressure of a gas component.

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