Molecule vs Formula Unit

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Victoria Luu - 1C
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Molecule vs Formula Unit

Postby Victoria Luu - 1C » Wed Oct 03, 2018 5:05 pm

On problem E21 in the 6th Edition, the ask us to find the "number of molecules and formula units." Does that mean that these terms are interchangeable? If not, what is the main difference between the two?

EllerySchlingmann1E
Posts: 76
Joined: Fri Sep 28, 2018 12:24 am

Re: Molecule vs Formula Unit

Postby EllerySchlingmann1E » Wed Oct 03, 2018 5:12 pm

Hi,

Molecules and formula units are not interchangeable, though they do refer to very similar things. Molecules refer to compounds in which the atoms are bonded covalently, while formula units refer to compounds with atoms that are ionically bonded. People tend to use "molecule" as a blanket term for compound, but there is a slight difference when talking about formula units. Hope that helps!

KHuang1L
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Molecule vs Formula Unit

Postby KHuang1L » Wed Oct 03, 2018 5:14 pm

Molecules and formula units are not interchangeable. Formula units are used to describe ions in ionic compounds.

lindsey_ammann_4E
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

Re: Molecule vs Formula Unit

Postby lindsey_ammann_4E » Thu Oct 04, 2018 5:21 pm

Essentially, when they are asking for the amount of molecules, they are referring to an element or something covalently bonded (think Na or O2). When they are asking for the amount of formula molecules, they are referring to an ionic compound (NaCl). You must use Avogadro's number for both situations, however, the phrasing differs slightly depending on what exactly you are calculating.

Ruiting Jia 4D
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am

Re: Molecule vs Formula Unit

Postby Ruiting Jia 4D » Thu Oct 04, 2018 11:55 pm

Adding on to the original post, how would you know to label an answer with "formula units" or "molecules"?


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