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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: joshua772 on March 09, 2016, 07:54:46 AM

Title: Finding the identity of unknown gas
Post by: joshua772 on March 09, 2016, 07:54:46 AM
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
Title: Re: Finding the identity of unknown gas
Post by: mjc123 on March 09, 2016, 08:27:49 AM
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.)
Title: Re: Finding the identity of unknown gas
Post by: joshua772 on March 09, 2016, 08:49:16 AM
Quote from: mjc123 on March 09, 2016, 08:27:49 AM
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 :<
Title: Re: Finding the identity of unknown gas
Post by: mjc123 on March 09, 2016, 12:15:33 PM
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.