(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A student working 3.0 m away from you in the chemistry lab creates a bad odour. The odour takes a while to get to you (assume that air currents are negligible). You then move 2.0 m further away, but the odour catches up with you in another 60 seconds. What is the diffusion coefficient of the molecules you smell?

hint: the root mean square distancee and the time must be measured from the source of the diffusing molecule.

2. Relevant equations

t= R^2 / 6D

3. The attempt at a solution

I first tried to find time from 0-3m by using the ratio between the two distances

2^2 / 6*s X 6T/^3 = 1 (1 since D is the same)

I found that t = 135s

I then added 135 to 60 seconds and used that as my total time and 5 as my total R and solved for D

D = R^2 / 6*T

= 25 / 6*195

=0.02136

However, my textbook says the answer is 0.044 and I don't see what I am doing wrong. :(

Any help will be much appreciated, thank you!

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# Homework Help: Find the Diffusion coefficient

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