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Topic: Mole Fraction  (Read 8628 times)

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Offline Shing

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Mole Fraction
« on: June 01, 2008, 03:48:20 PM »
The partial pressure of CH4 is 0.175atm and partial pressure of O2 is 0.250 atm in a mixture of gases.. what is the mole fraction of each gas in the mixture?

What I did was that i divided the partial pressure of each gas in the mixture by the total pressure.

Mole fraction of CH4 : 0.175atm/ 0.425atm
Mole fraction of O2: 0.250 atm /0.425atm

Is this correct??
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Offline Borek

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Re: Mole Fraction
« Reply #1 on: June 01, 2008, 03:58:38 PM »
OK
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Offline Shing

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Re: Mole Fraction
« Reply #2 on: June 01, 2008, 04:01:24 PM »

Offline Borek

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Re: Mole Fraction
« Reply #3 on: June 01, 2008, 04:50:06 PM »
It means its OK ;)

Yes, looks right to me.

As usual, could mean I am missing something.
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Offline Shing

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Re: Mole Fraction
« Reply #4 on: June 01, 2008, 05:24:23 PM »
It means its OK ;)

Yes, looks right to me.

As usual, could mean I am missing something.
The Whole Question is...

The partial pressure of CH4 is 0.175atm and partial pressure of O2 is 0.250 atm in a mixture of gases..
a) what is the mole fraction of each gas in the mixture?
b) If the volume of teh mixture is 10.5 L At 65 deg C, calculate total number of moles of gas in the mixture
c) Calculate grams of each gas in the mixture.

What I did:

partial presure / total pressure
a) mole fraction of CH4 := 17.7kPa/43.02kPa
                      of O2 := 25.3 kPa/ 43.02 KPa

b) V- 10.5 L
    T = 338 K
    P = 43.02 kPa (total)
so using PV=nRt
n= PV/RT
n= 0.160 mol

c) using the mole fraction
moles of CH4 present := 17.7/43.02 * 0.160 = 0.065 mol
moles of CH4 present := 25.3/43.02 * 0.160 = 0.094 mol

mass of CH4 = 0.065 mol * 16g/mol (molar mass) = 1.04 g
mass of O2 = 0.094mol * 32g/mol = 3.0 g

Offline Borek

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Re: Mole Fraction
« Reply #5 on: June 01, 2008, 05:43:45 PM »
I got differences on last digits - for example total seems to be 0.161, not 0.160.

Generally OK.

I mean - right.
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Offline Shing

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Re: Mole Fraction
« Reply #6 on: June 01, 2008, 05:46:56 PM »
I got differences on last digits - for example total seems to be 0.161, not 0.160.

Generally OK.

I mean - right.

Thank you.

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