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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: laxplayer on November 07, 2007, 06:15:54 PM

Title: Partial Pressure Calculation
Post by: laxplayer on November 07, 2007, 06:15:54 PM

The problem states:
A mixture of gases contains 5.84 g of N2, 5.31 g of H2, and 8.21 g of NH3. If the total pressure of the mixture is 2.86 atm, what is the partial pressure of each component?

I know that all of the pressures have to add up to 2.86 atm because of Dalton's Law, but that's about it :] I don't understand how you go from grams of a substance to finding pressure of it, without knowing the temperature or volume.

Title: Re: Partial Pressure Calculation
Post by: Borek on November 07, 2007, 06:34:08 PM

Do you know what mole fraction is and how it is related to partial pressure?

Title: Re: Partial Pressure Calculation
Post by: laxplayer on November 07, 2007, 06:59:39 PM

Aren't the mole fractions the moles of one substance over the moles of the total? But I don't know how they're related.

Title: Re: Partial Pressure Calculation
Post by: Borek on November 07, 2007, 07:09:51 PM

http://en.wikipedia.org/wiki/Partial_pressure

Title: Re: Partial Pressure Calculation
Post by: laxplayer on November 07, 2007, 08:20:31 PM

oh, so they're equal. P₁/P=n₁/n right? So does that mean (.2084 mol N2)/(3.32433 mol total)=(X atm N2)/(2.86 atm total)?

Title: Re: Partial Pressure Calculation
Post by: laxplayer on November 07, 2007, 08:45:58 PM

It says I got it right!  ;D