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Homework Help: How many Cr atoms in 78.82 g potassium dichromate?

  1. Sep 26, 2006 #1
    How many Cr atoms in 78.82 g potassium dichromate?
    Potassium dichromate is [tex]\textrm{K}_{2}\textrm{Cr}_{2}\textrm{O}_{7}[/tex].

    I said:

    The molecular mass of potassium dichromate is:
    39.1*2+52*2+16*7=294.2

    So, in 78.82 g potassium dichromate, there are 78.82/294.2= 0.2680 moles of potassium dichromate. Each mole of potassium dichromate has [tex]6.022~x~10^{23}[/tex] molecules, each with 2 chromium atoms. So, in one mole, there are [tex]1.204~×~10^{24}[/tex] chromium atoms. So, in .2680 moles, there are [tex].2680(1.2044~×~10^{24})~=~3.228~×~10^{23}[/tex], correct?

    As a sidenote, it appears that LaTeX graphical formulas can't be seen in the preview mode -- the only way to check them is to post the message then edit the message if they're wrong? Also, where can I find a better LaTeX tutorial than https://www.physicsforums.com/misc/howtolatex.pdf which just doesn't give enough information? Ah, https://www.physicsforums.com/showthread.php?t=9021 has some pretty good information, but I still don't seem to be doing my LaTeX correctly.
     
    Last edited by a moderator: Apr 22, 2017
  2. jcsd
  3. Sep 26, 2006 #2
    Yes, that looks good. And I don't currently know of any better LaTeX tutorial, I've just been learning it recently too and would also be interested in a more in depth tutorial.
     
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