1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Amount in mol of compound ions

  1. Dec 19, 2007 #1
    [SOLVED] Amount in mol of compound ions

    This is just a quick question as it has slipped my mind..

    Does anyone know how you would find the mol of a compound ion (ie - SO42- (sulfate ion)), if you are given the mol of the whole compound (in my case it is K2SO4)

    I know to find single ions and atoms (ie of potassium and Oxygen) you just multiply their number by the amount of mol, however i am less sure of the compound ions...

    Do you treat the compound ion, in this case...as having a subscript of 1? therefore you would multiply the amount in mol by 1?

    thank you..
  2. jcsd
  3. Dec 20, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I think you have solved your own problem.
  4. Dec 20, 2007 #3
    Yeah i may have...haha

    The problem is...I'm making sure because the answer at the back of my book I know is wrong...So i have nothing to check against
  5. Dec 20, 2007 #4
    what is the actual question?
  6. Dec 20, 2007 #5
    Some dimensional analysis makes it intuitive

    [tex]#mol (K_2SO_4) * \frac{1 mol SO_4}{1 mol K_2SO_4}[/tex]

    That fraction is equal to 1 since there is exactly 1 mol of SO4 in every mol of K2SO4

    The mol K2SO4 cancel out and you have what you're looking for
  7. Dec 20, 2007 #6
    The given question was not worded well

    But i understand now that in a compound such as K2SO4, you would treat SO4^2- as one ion in this compound....therefore you would multiply 1 by the number of mol there is of K2SO4..

    Problem solved.....thanks guys
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook