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Rate of Effusion

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**MilkyCar**:

I'm stuck on this problem and I've been attempting to solve it.

So it says:

It took 9.2 minutes for 4.0 L Neon to effuse through a porous barrier. How long will it take for 4.0 L of Cl2 gas to effuse under identical conditions?

I did 4.0L/9.2 to get 0.435 as the rate of effusion of neon. I took that and then did 0.435/sqrt(70.9/20.2) to get 0.0353 L.

I then did 4.0 L/0.0353 L/min to get 113.3 minutes.

I'm assuming my calculations must be off and I'm not sure what the right answer actually is and what else I'm supposed to do to solve it.

**mjc123**:

Try doing your calculation again. (It might have something to do with the order you put things into a calculator.)

Cl2 has a bit less than 4x the MW of neon, so you'd expect the effusion rate to be about half. It's a good idea to regularly do these ball-park sanity checks to indicate quickly if the answer you get is clearly wrong.

**Vidya**:

--- Quote ---I took that and then did 0.435/sqrt(70.9/20.2) to get 0.0353 L.

--- End quote ---

I think you did error here.

Rate of effusion of chlorine = 0.453 (20.2/70.9)1/2

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