Question

A gas evolved from the fermentation of glucose is found to effuse through a porous barrier in 15.0 min.

Under the same conditions of temperature and pressure, it takes an equal volume of N2 12.0 min to effuse through the same barrier. Calculate the molar mass of the gas.

Answer 1

what's given here is time not rate so i use the formula \[\huge \frac {t_1}{t_2} = \sqrt{\frac{M_1}{M_2}}?\]
or is it \[\huge \frac{t_2}{t_1}= \sqrt{\frac{M_1}{M_2}}\]
i cant ind the formula in the net..

Answer 2

find*

Answer 3

Assuming both gasses must diffuse the same measure of distance: The top one.

Answer 4

ahh so time is directly proportional to molar mass huh

Answer 5

^Square root of molar mass, yes, like in the first formula.

Answer 6

\[M_1 = 43.78 g/mol\]
is that right?

Answer 7

@dominusscholae how would i find the root-mean-square of N2? do you have an idea how?

Answer 8

You mean root-mean-square velocity?

Answer 9

yup

Answer 10

It's \[\sqrt{3RT/M}\] M the mass of N2

Answer 11

is that a formula?`

Answer 12

Yep

Answer 13

i dont think that's applicable here though...i have no R or T right?

Answer 14

You don't need it. You have the equation above to help you lol.

Answer 15

In your first post.

Answer 16

\[\frac{t_1}{t_2} = \sqrt{\frac{M_1}{M_2}}?\]

Answer 17

how can i use that?

Answer 18

You have the time of effusion for N2, the time of effusion for the unknown gas, and the mass of N2 (which you can calculate).

Answer 19

i do not see where you are going..

Answer 20

Plug t1 = 15.0 min , plug t2 = 12.0 min , plug M2 = 28.02 g/mol

Answer 21

wouldnt M1 be the only thing left then?

Answer 22

how would plugging it in help me find the root-mean-square speed?

Answer 23

\[\frac{15}{12} = \sqrt{\frac{M_1}{28.02}}\]

how can i solve for rms??

Answer 24

\[\frac{15}{12} = \frac{\sqrt{M_{1}}}{\sqrt{28.02}} \]
you should be able to solve for \(M_1\) now :)

Answer 25

im not solving for M1 i've already solved for m1

Answer 26

im asking for the root-mean-square

Answer 27

define "root-mean-square"?

Answer 28

idk...

Answer 29

im asking arent i

Answer 30

http://en.wikipedia.org/wiki/Root_mean_square
i dont see how that is related to chemistry :/

Answer 31

so you dont know how to solve this @Mimi_x3 huh...simple algebra she says -_-

Answer 32

15/12 = 1.25
1.25 x sqrt 28.02 = 6.6
6.6^2= 43.78, more or less the molar mass of CO2.
Mimi was right, just use algebra to solve for m1 but apparently you're incapable. idiot