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### Question Regarding Moles

Posted: Wed Apr 04, 2018 7:06 pm
Hi guys! I am having trouble understanding question E.23 part C , if anyone can help explain how to find the amount of F- ions in 25.2kg of UF6 or how to set it up to find an answer I would really appreciate it!

### Re: Question Regarding Moles

Posted: Wed Apr 04, 2018 10:06 pm
The way I did is I just went ahead and ignored the (-) sign on F- and calculated as if I would any other problem (like part A B and D) and it gave me the answer (on the back of the textbook).

the U in UF6 is Uranium on the periodic table. Figure out the molar mass of both Uranium and Fluorine, then you can get the molar mass of UF6. From there you can use the molar mass of UF6 to find out how many moles of UF6 are in 25.2kg. Once you figure this out, just multiply the number by six as 1 mole of UF6 contains 6 moles of F-. Maybe the - sign confused you?

I believe that F- is just the way of denoting the fluorine ion, which is negatively charged. Fluorine is a highly reactive element in the halogen family from the periodic table. It's most outer electron shell (valence electrons) lacks 1 electron just like other halogens (that's why they're super reactive). Due to the natural tendency for elements to try and "fill" their outer electron shell, fluorine will usually "pull" a valence electron from another element causing the atom to have a negative charge, as the atom will now hold more electrons than protons. In the case of the question above, it's probably pulling an electron from the Uranium. That's why it's notated as F- I think you can read up a little more on this on section C.3 starting on page F27.

### Re: Question Regarding Moles

Posted: Thu Apr 05, 2018 9:48 am
yes joshua is correct

### Re: Question Regarding Moles

Posted: Thu Apr 05, 2018 8:31 pm
Thank you!!