How do I find the volume of gas using the given mass of oxygen?

[thevinciz]

Homework Statement

Homework Equations

The Attempt at a Solution

I have tried to change mass of oxygen into mol and I got ratio of oxygen and nitrogen. And I don't really know what to do.

 

[Chestermiller]

Homework Statement

View attachment 225654

Homework Equations

The Attempt at a Solution

I have tried to change mass of oxygen into mol and I got ratio of oxygen and nitrogen. And I don't really know what to do.

In common terminology, the term volume fraction is used synonymously with mole fraction.

 

[thevinciz]

Well done.

Now try using Ideal gas law. Use the mole ratio you obtained.

Could you explain more?

 

[thevinciz]

In common terminology, the term volume fraction is used synonymously with mole fraction.

Do you mean mol of oxygen / mol of nitrogen is equal to volume of oxygen / volume of nitrogen? But I still don't know how to solve.

 

[Chestermiller]

Do you mean mol of oxygen / mol of nitrogen is equal to volume of oxygen / volume of nitrogen? But I still don't know how to solve.

Let's see the details of what you did.

 

[thevinciz]

Let's see the details of what you did.

I got molO2/molN2 = 2.8/12.8 and from your comment I understand that volumeO2/volumeN2 = 2.8/12.8

 

[Chestermiller]

I got molO2/molN2 = 2.8/12.8 and from your comment I understand that volumeO2/volumeN2 = 2.8/12.8

This is incorrect. If you take as a basis 1 kg of gas mixture, what is the mass of oxygen in the mixture? What is the mass of nitrogen in the mixture? What are the number of moles of oxygen in the mixture? What are the number of moles of nitrogen in the mixture? What is the mole fraction oxygen? What is the mole fraction nitrogen?

 

[thevinciz]

This is incorrect. If you take as a basis 1 kg of gas mixture, what is the mass of oxygen in the mixture? What is the mass of nitrogen in the mixture? What are the number of moles of oxygen in the mixture? What are the number of moles of nitrogen in the mixture? What is the mole fraction oxygen? What is the mole fraction nitrogen?

In 1kg ,mass of O2 = 0.2 kg
mass of N2 = 0.8 kg
mole of O2 = 12.5
mole of N2 = 28.6

So total mole is 41.1 : mole fraction O2 = 12.5/41.1
mole fraction N2 = 28.6/41.1

 

[Chestermiller]

In 1kg ,mass of O2 = 0.2 kg
mass of N2 = 0.8 kg
mole of O2 = 12.5

Moles O2 = 6.25

 

[thevinciz]

Moles O2 = 6.25

I see

 

[thevinciz]

Moles O2 = 6.25

Thanks I got the answer now, is it 6.25/6.25+28.6 right?