Formula Units: Molecules or Atoms

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marisaimbroane1J
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Joined: Fri Sep 28, 2018 12:23 am

Formula Units: Molecules or Atoms

Postby marisaimbroane1J » Mon Oct 01, 2018 12:39 am

There are several homework problems that require using Avogadro's Number to convert moles to formula units. I know that whether you write the answer in terms of molecules or atoms it will be the same, but are there certain cases where your final answer should be in terms of one or the other?

timothy_ho_4B
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

Re: Formula Units: Molecules or Atoms

Postby timothy_ho_4B » Mon Oct 01, 2018 12:41 am

It mainly depends on whether the question specifically asks for molecules or atoms. Obviously, if the question refers to a single element, then it would be atoms. Otherwise, it mainly depends on what the question asks for.

marisaimbroane1J
Posts: 69
Joined: Fri Sep 28, 2018 12:23 am

Re: Formula Units: Molecules or Atoms

Postby marisaimbroane1J » Mon Oct 01, 2018 8:48 am

If the question does not specifically ask for either then you can just choose either one then? (Assuming it is not a single element)

Raymond Ko 1H
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Joined: Fri Sep 28, 2018 12:19 am

Re: Formula Units: Molecules or Atoms

Postby Raymond Ko 1H » Mon Oct 01, 2018 11:52 am

Kind of like what Timothy said, you'd want to see what "things" the problem is dealing with. For example, if the question was asking for the number of H2O, you'd want the answer in molecules because it would be incorrect to say a certain number of H2O "atoms". If the question was asking for the number of C, the answer would be in atoms.

Avery Zuelch 1D
Posts: 31
Joined: Fri Sep 28, 2018 12:18 am

Re: Formula Units: Molecules or Atoms

Postby Avery Zuelch 1D » Tue Oct 02, 2018 6:32 pm

In the converting process, when/where do you use Avogadro's Number? I know the general steps in this process, but get quite confused when it is time to divide/multiple by it.

Josephine Lu 4L
Posts: 62
Joined: Fri Sep 28, 2018 12:18 am

Re: Formula Units: Molecules or Atoms

Postby Josephine Lu 4L » Tue Oct 02, 2018 6:48 pm

I'm confused about what exactly are formula units too. On problem E9 part b, the answer is written in terms of atoms as formula units, but isn't MgSO4 * 7H2O a molecule?


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