Question

A mixture of methane and ethane is contained in a glass bulb of 500cm^3 capacity at 25 degrees c. the pressure is 1.25 bar and the mass of the gas in the bulb is .530g.
a) what is the average molar maass of the gas? (21.0g/mol)

b) what is the mole fraction of methane?

Answer 1

I need help with b

Answer 2

for a i used the following equation

\[M=\rho(\frac{RT}{p})\]

Answer 3

you have to set up an equation using their (ethane and methane) molar masses, and moles and mass, like:

\(M_{Et}*n_{Et}+M_{Me}*n_{Me}=m_T\)

try playing around with that and their mole fraction equation.

Answer 4

So I used pv=nrt to get there was .025219 mols how do i find the moles of each gas?

Answer 5

what have you tried?

Answer 6

the only thing I have figured out was the total number of moles in the solution. I am not really sure how to get the other information needed to find the molefraction. I have looked online and can't really figure out anything.

Answer 7

it's likely that you have to write 2 equations using the info you have and substituting one into the other.

Answer 8

so what i'm essentially saying is that you have to use your math skills for this question.

Answer 9

oh i see what you are saying

Answer 10

well thanks for the help and I will report back if I figure anything out

Answer 11

okay, i just don't wanna be doing your work. If you honestly try it and don't get it, post back and i'll help you figure it out.

Answer 12

I did manage to figure it out and the advice you gave earlier was correct I was just unable to see the rest of the needed info. Using the equation

\[1= \chi_E + \chi_m\]

you can rearrange that to,

\[1-\chi_M=\chi_E\]

Then you can plug it into the equation you gave me earlier. Thanks for the help again and sorry I couldn't make the connection.