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Figuring out formula from looking at name

  1. Sep 23, 2010 #1
    For example, is there any way to know that aluminum sulfate has the formula of Al2(SO4)3 just by looking at the name "Aluminum Sulfate"? It seems like while doing chemistry problems, the problems kind of assume you can do that.

    Thanks.
     
  2. jcsd
  3. Sep 23, 2010 #2

    CompuChip

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    Well, aluminium ions are Al3+ and sulfate is (SO4)2-. So the only way to combine them and get something neutral back, is in the ratio 2 : 3.
     
  4. Sep 23, 2010 #3

    Entropee

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    Right, so Al2 makes it now a +6 charge and (SO4)3 will have a -6 charge. But you do in fact need to remember Al is Aluminum and SO4 is Sulfate. But as far as the charges, we were always allowed to look at the periodic table for those. We had a whole week where we just memorized different things like carbon dioxide, water, methane, ethane, oxalate, sulfate, sulfite, etc. If you weren't required to do so I would suggest doing it anyways, it makes chem WAY easier.
     
  5. Sep 23, 2010 #4
    Thanks for the responses guys.
    Is there like a list of all of them somewhere for me to study? What are they called? I'll go look it up.
    I do need to learn that stuff, because when I see "sulfate" all I know is it's sulfur.
     
  6. Sep 23, 2010 #5

    Entropee

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    I didn't actually watch this video lol, but im sure it will be helpful. If not, basically everything you need to remember is on the board behind him. Except I don't think methane was on his list, which is CH4. If you need any more help just ask.
     
    Last edited by a moderator: Sep 25, 2014
  7. Sep 23, 2010 #6
    Awesome, thanks. This forum is making me more and more un-retarded every day.
     
  8. Sep 24, 2010 #7

    Entropee

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    Yeah no lie, i'm gonna ask so many math questions when i get to precalc (I suck at math) although this college algebra stuff is easy so far.
     
  9. Sep 24, 2010 #8
    I wrote all of those down, but I noticed they're all charged molecules. Is there a reason for that? You mentioned methane isn't on the list, and since it's not charged, maybe that's why.
     
  10. Sep 24, 2010 #9

    Borek

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    They are called ions :wink:

    --
     
  11. Sep 24, 2010 #10

    Entropee

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    Yes they are but remember a lot of times you have to combine them with ions and anions and balance them out. Also what borek says is correct but I believe many of them have negative charges too (anions).
     
  12. Oct 5, 2010 #11
    Just to clear things up... Ions with a positive charge are called cations and ions with a negative charge are called anions (As you rightly said).

    :)
     
  13. Oct 5, 2010 #12

    Entropee

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    Ah yes forgive me, I forgot they were called cations, been a while now.
     
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