Question

Under certain conditions, neon (Ne) gas diffuses at a rate of 7.0 centimeters per second. Under the same conditions, an unknown gas diffuses at a rate of 4.9 centimeters per second. What is the approximate molar mass of the unknown gas?

Answer 1

6.5 g/mol

11 g/mol

20 g/mol

41 g/mol

Answer 2

use grahams law of diffusion: \(\large \dfrac{rate_1}{rate_2}=\sqrt{\dfrac{M_2}{M_1}}\)

M=molar mass

Answer 3

so 7.0/4.9 = ?/20.17

Answer 4

@aaronq

Answer 5

yep, but dont forget the squared root

Answer 6

do you know how to solve for \(M_2\)?

Answer 7

Nope

Answer 8

okay, it's just algebra

\(\large\dfrac{rate_1}{rate_2}=\sqrt{\dfrac{M_2}{M_1}}\)

square both sides

\(\bigg(\large\dfrac{rate_1}{rate_2}\bigg)^2=\bigg(\sqrt{\dfrac{M_2}{M_1}}\bigg)^2\)

the squared root sign cancels by squaring it

\(\bigg(\large\dfrac{rate_1}{rate_2}\bigg)^2=\dfrac{M_2}{M_1}\)

move \(M_1\) over

\(\large M_2=M_1*\bigg(\large\dfrac{rate_1}{rate_2}\bigg)^2\)

Answer 9

M2 = 41.14?

Answer 10

yup

Answer 11

So I got 1.42

Answer 12

Which isn't an answer, so is there something I do next?

Answer 13

your answer was \(M_2\) = 41

Answer 14

Oh

Answer 15

Thank you!