Question

A gaseous mixture of O2 and N2 contains 34.8% nitrogen by mass. What is the partial pressure of oxygen in the mixture if the total pressure is 465 mmHg?

Answer 1

0.348 x 465 mm = partial pressure N2.
partial pressure O2 = 465 - partial pressure N2 OR
partial pressure oxygen = 465 x (1.00 - 0.348) =

Answer 2

This is incorrect, It says "by mass" not "by moles". therefore you must find the number of moles and use the mole fraction

Answer 3

First you find the moles of N2 assuming that you have 34.8 grams of N2. Then you find the moles of O2 assuming that you have 65.2 grams of O2.(100%-34.8%=65.2% so there is 65.2g O2). The partial pressure equals mole fraction x the total pressure(mole fraction= moles of O2/total moles in mixture) so in the end you multiply 465mmHg x mole fraction and theres your answer. :)