Question

A sample of air (containing 20% 02and 80% N2) is dissolved in water when total pressure of air is 1atm
The solubility of N2and 02( in terms of mole fraction) is x and y. This sample is taken at height of H
above sea level where pressure of air is 0.4 atm and temperature is 300 K and solubility of N2 and O2
in terms of mole fraction) Is X and y. Assume that value of Henry's constant remains same at sea level
and H. The value of 2(x/X+y/Y) is

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Answer 1

Answer:

Here's what I got.

Explanation:

For starters, you know that the partial pressureof a gas that's part of a gaseous mixture can be calculated using the following equation--think Dalton's Law of Partial Pressures here!

Pi=χi⋅Ptotal−−−−−−−−−−−−

Here

Pi is the partial pressure of gas i

χi is the mole fraction of gas i in the mixture

Ptotal is the total pressure of the mixture

Now, you know that you have a sample of air at a total pressure of 1 atm and that 21% of all the molecules of gas that make up this sample are molecules of oxygen gas.
In order to be able to calculate the partial pressure of oxygen gas, you need to figure out the mole fraction of oxygen gas in the sample. The mole fraction of oxygen gas is calculated by dividing the number of moles of oxygen gas by the total number of moles of gas present in the sample.

χO2=moles of O2total moles of gas (*)

As you know, Avogadro's constant allows you to convert the number of molecules to moles.

Avogadro's constant−−−−−−−−−−−−−−−−−−1 mole gas=6.022⋅1023  molecules gas−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

So, let's assume that this sample contains Nmolecules of gas. Since 21% of these molecules are molecules of oxygen gas, you can say that this sample contains

Nmolecules gas⋅21 molecules O2100molecules gas=(21⋅N100)  molecules O2

This means that the number of moles of oxygen gas present in the sample is equal to

(21⋅N100)molecules O2⋅1 mole O26.022⋅1023