Question

A gaseous mixture of and contains 30.8 nitrogen by mass. What is the partial pressure of oxygen in the mixture if the total pressure is 505mmHG ?

I am getting .41 * (505/750)= .27

.27 is my answer, is this right.

Answer 1

30.8 percent N2 by mass
69.2 precent O2 by mass

Now you need to convert those to moles

Assume 1000 g total
308/28=moles of N2
692/32 moles of O2

Now do those moles as a percent of total moles.

Then, multiply 505mmHg by the percent of O2 moles.