Winter 2013 final Q4B

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Blake_Panter_3D
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Winter 2013 final Q4B

Postby Blake_Panter_3D » Wed Mar 15, 2017 5:23 pm

Can someone explain how to find the change in the concentrations of O2 for each droplet after 100s? The equations the solutions has don't make conceptual sense to me.

Andrew Nguyen 3G
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Joined: Wed Sep 21, 2016 2:59 pm

Re: Winter 2013 final Q4B

Postby Andrew Nguyen 3G » Wed Mar 15, 2017 5:45 pm

Dr. Lavelle mentioned problem solving today in lecture and this is an example of what he is talking about. From what I know, I don't think we learned how to directly solve problems like these in the course reader before. But it makes sense that:

[Current] = [Initial] + [Change in initial]

So:

[O2] = [O2 initial] + [change in initial O2]

Flip both equations:

1 / [O2] = 1 / ([O2 initial] + [change in initial O2])

Since Q = [Products] / [Reactants] = 1 / [O2], plug in:

Q = 942.23 = 1 / ([.00117] + [Change in initial O2])

Rearrange and solve using algebra.

tapasyat
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Joined: Fri Sep 25, 2015 3:00 am

Re: Winter 2013 final Q4B

Postby tapasyat » Sat Mar 18, 2017 11:27 am

Wait why is there a 1 for the product? How do we know it's not the other way around/0/any other number?

EllisJang2O
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Postby EllisJang2O » Sat Mar 18, 2017 11:45 am

Blake_Panter_3D wrote:Can someone explain how to find the change in the concentrations of O2 for each droplet after 100s? The equations the solutions has don't make conceptual sense to me.


If you look at the original equation 2Fe(s)+ 2H2O(l) + O2(aq) ---> 2Fe(OH)2(s), you'll know how to write Q because Q = [products]/[reactants]
Since liquids and solids are not included, Q = 1/[O2]


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