Empirical Formula Problem Solving

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timschaeffer Dis 1J
Posts: 38
Joined: Fri Sep 28, 2018 12:18 am

Empirical Formula Problem Solving

Postby timschaeffer Dis 1J » Thu Nov 08, 2018 9:35 pm

When solving for the empirical formula, what do you do when you have the moles of each atom but they're all really close in value or don't seem to follow any obvious ratio? I wasted a lot of time on this final step during the midterm. Does anyone have any good strategies for finding the answer quickly?

Kessandra Ng 1K
Posts: 67
Joined: Fri Sep 28, 2018 12:25 am

Re: Empirical Formula Problem Solving

Postby Kessandra Ng 1K » Thu Nov 08, 2018 10:45 pm

If the moles of each atom are basically the same and near an integer value, then you can just go off those to find your empirical formula.

If the moles of each atom don't seem to follow any obvious ratio, you'll just have to trial and error different numbers to multiply the mole ratios by to get near an integer value. Dr. Lavelle also said that he wouldn't give extremely hard numbers to work with in these calculations, so hopefully we'll also get good numbers for the final!

Jessica Chen 1F
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: Empirical Formula Problem Solving

Postby Jessica Chen 1F » Thu Nov 08, 2018 10:45 pm

I would divide all the moles by the smallest value, and set that small value as x. The other values would then be multiples (not necessarily integer) of x. I would then try to multiply all these multiples of x by a number to get whole numbers. There's really no easy way besides trial and error for the last step.
Here's what it would look like for a mock question:

C: 3.0 (moles) --> 6x
H: 1.5 (moles) --> 3x
O: 0.5 (moles) --> x

C6H3O


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