Molecular Formula

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Sophia Dinh 1D
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Joined: Thu Jul 25, 2019 12:15 am

Molecular Formula

Postby Sophia Dinh 1D » Thu Oct 03, 2019 2:22 pm

If you're given the molecular mass for the compound and the mass percentages can you multiply the percentages into the molecular mass and find the grams of each compound that way or do you have to assume 100g?

Posts: 52
Joined: Wed Sep 11, 2019 12:16 am

Re: Molecular Formula

Postby TYun_1C » Thu Oct 03, 2019 2:33 pm

Theoretically, you could multiply the percent by the molecular weight since every element would still be in the same ratio, but it would just add an extra step to the calculation. It's usually easier to just assume that the sample is 100 grams since the percentages are portioned out of 100. Even if you multiplied molecular weight by each individual percentage, the would would ultimately have to divide the molecular weight by the weight of the empirical formula to figure out the molecular formula since when you divide the moles by the smallest mole, you are looking for the smallest ratio of each element in the compound. Hope this helps!

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