Alternative way to solve for F.19

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Tiffany Chen 1A
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Joined: Fri Apr 06, 2018 11:02 am
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Alternative way to solve for F.19

Postby Tiffany Chen 1A » Sat Apr 07, 2018 5:16 pm

I solved for the molecular formula differently than the other students that replied in the other post about this homework question and I just wanted to make sure that my method of solving was ok. Instead of solving for the empirical formula first and then solving for the molecular formula, I just solved for the molecular formula directly from the info given.

I multiplied the percent of each element by the molar mass of caffeine (194.19) then divided that by the molar mass of each element, respectively, to solve for the number of atoms of each element in caffeine.
So for carbon I did (194.19)(0.4948)/(12.01) = 8 (it's not exactly 8 but it's extremely close to 8) and then repeated this for H, N, and O.

I still got C8H10N4O2 as my answer, so is it ok to solve for the molecular formula this way?

Angela Ueng 1E
Posts: 3
Joined: Fri Apr 06, 2018 11:05 am

Re: Alternative way to solve for F.19

Postby Angela Ueng 1E » Sat Apr 07, 2018 5:51 pm

I think that it should be fine, considering you still got the right answer. On tests and exams, though, it's probably better to show your work using the steps outlined in class.

Chem_Mod
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Re: Alternative way to solve for F.19

Postby Chem_Mod » Sun Apr 08, 2018 11:47 am

The way you solved is completely fine as long as the molar mass is already provided. That is the shortest route to an answer.

Tiffany Chen 1A
Posts: 36
Joined: Fri Apr 06, 2018 11:02 am
Been upvoted: 1 time

Re: Alternative way to solve for F.19

Postby Tiffany Chen 1A » Sun Apr 08, 2018 5:43 pm

Thanks!


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