A sample of Xe takes 75s to effuse out of a container. An unknown gas takes 37 seconds to effuse out of an identical container, same conditions. What is the identity of the gas?

asked by @jeremyb10 • about 1 year ago • ChemistryEffusion • 5 pts

I label Xe as A and unknown as B and went through the problem as such... My answer came out to 539, however the correct answer is Oxygen (32)... What am I doing wrong here?

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1 answer

Hey Jeremy! So this was definitely a tricky question. Notice that you're given the seconds it takes each gas to effuse out of the container. Usually for these problems, you'll be given the rate ratio or something similar.

Notice that rate=amount/time. This is why your answer wasn't adding up, but you had the right idea! Say you plug in 1 for the amount since it is not given, and you place the seconds as the denominator. This will give you a new rate for each: 1/75 and 1/37 for Xe and the unknown gas, respectively. Now you can plug that into the equation that I used in the video you saw. I also attached the solution just so you can visualize it.

Hope this helps! Please let us know if you have any other questions :)

enter image description here

answered by @sabrina • about 1 year ago
  • Perfect. Thanks! Jeremy commented about 1 year ago
  • No problem :) Sabrina commented about 1 year ago