[joshua772]

my teacher just got a question in the world wide web and changed it from 0.355 to 0.255

An unknown gas composed of homonuclear diatomic molecules effuses at a rate that in only 0.255 times that of O2 at the same temperature. what is the identity of unknown gas.

rx/rO2 = sqr mO2/M
rx = 0.255 x rO2

rx/rO2 = 0.255 = sqr 32.0g/mol / mx

solving for uknown molar mass
Mx :
32.0g/mol / mx = (0.255)^2 = 0.065025

Mx = 32.0g/mol / 0.065025 = 492.11 g / mol which is ? gas and cant find it on internet

[mjc123]

Did your teacher just make a mistake? There is an answer for 0.355 - can you find it? (There is also another answer that is not a homonuclear diatomic.)

[joshua772]

Did your teacher just make a mistake? There is an answer for 0.355 - can you find it? (There is also another answer that is not a homonuclear diatomic.)

we got an answer for 0.355 and it's Iodine. but our teacher still pushing for 0.255 :<

[mjc123]

For a homonuclear diatomic? That's ridiculous. It would have to be something like Cm₂. At₂ would be too light, Uus₂ too heavy (apart from not existing long enough to measure its diffusion). Even if you remove the restriction to homonuclear diatomics, I can't think of anything.