Mass % Composition

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Mass % Composition

Postby Katie_Ho_1M » Sun Oct 30, 2016 3:08 pm

Is it necessary to calculate the mass % composition if given the grams of each element in a compound? I found that if you skip that step and go directly to converting grams into moles, you would still end up with the same ratios and thus the same answer. Would we have to show mass % comp on the midterm when it doesn't explicitly state that you need to find it?

Natalie Rotstein 3J
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Re: Mass % Composition

Postby Natalie Rotstein 3J » Sun Oct 30, 2016 9:00 pm

I doubt we would need to when we can just do it the way you said. Generally, I think the % mass composition would be the information given if in a problem where we need to find the empirical formula as opposed to chemical formula, because empirical is just ratios of atoms as opposed to the actual number of atoms in the molecule. If it isn't necessary to solve a problem, I doubt it would be necessary to show it (unless specifically stated in the problem).

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Re: Mass % Composition

Postby Alejandra_Vasquez_1B » Sun Oct 30, 2016 9:25 pm

It is unnecessary to calculate the % mass composition when you are given the grams because you can just go from grams to moles. It is a lot quicker to use the grams to convert to moles rather than finding % calculate composition. (You also save time in your calculations.)

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Re: Mass % Composition

Postby Joslyn_Santana_2B » Sun Oct 30, 2016 10:00 pm

On the sample midterms, it gives the solution in both versions of calculating. Also, my PLF said you can calculate it either way.

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