Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Molarity notation

  1. Apr 5, 2005 #1
    What does the following notation (to the power of -1) mean? TiA

    ex. [tex] [Na] = 0.050 mol L ^{-1}[/tex]
     
  2. jcsd
  3. Apr 5, 2005 #2
    I have another question (did not want to create a new thread):

    "What is the ratio x:y when the equation below is properly balanced?"

    [tex]xSn^{2+}(aq) + y Ag^{+}(aq) -> n Sn^{4+}(aq) + m Ag^{+}(s)[/tex]

    I've never seen a question like this before... an explanation or a link to a site or something would be greatly appreciated.
     
  4. Apr 5, 2005 #3
    "L^-1" means "per liter." 0.05 mol/L is 0.05 M.
     
  5. Apr 5, 2005 #4

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    For the first post,it's simply the unit 'liter' (which should be shortened 'l',not 'L' (that stands for length)) raised to the power "-1".

    For the second,i'm sure u miss the negative ions...Silver ion is a spectator in a redox ionic reaction.I don't see a connection between "x" & "y".And next time use [itex] \rightarrow [/itex] (code \rightarrow).

    Daniel.
     
  6. Apr 5, 2005 #5
    Simply balance the equation and give the ratio of x to y. This is a re-dox reaction. They're usually solved using the method of "half-reactions."
     
  7. Apr 5, 2005 #6
    Ooooops! I thought that was "Ag," not "Ag+"....and there is something wrong, here. Sn(+4) + 2Ag -> Sn(+2) + 2Ag(+) might be the reaction, but not what you have.
     
  8. Apr 5, 2005 #7

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    That's what i said above and it seemed weird to me,too that "Ag" doesn't undergo either reduction or oxdation.

    Daniel.
     
  9. Apr 5, 2005 #8
  10. Apr 5, 2005 #9

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Yeah,a typo in YOUR POST...

    [tex] Sn^{2+}_{(aq)} + Ag^{+}_{(aq)}\rightarrow Sn^{4+}_{(aq)}+Ag\downarrow [/tex]

    Now you can do the redox properly...

    Daniel.
     
  11. Apr 6, 2005 #10

    Borek

    User Avatar

    Staff: Mentor

  12. Apr 6, 2005 #11

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Nope,it's incorrect.It's the same way they teach "k" instead of "K" for Kg...It's outrageous.

    Daniel.
     
  13. Apr 6, 2005 #12

    Borek

    User Avatar

    Staff: Mentor

    Have you read comment on the NIST page? L was adopted in 1979 and is internationally accepted. So it is correct.

    IUPAC lists both forms just like NIST does:

    http://www.iupac.org/reports/1993/homann/units51.html

    I was taught l 30 years ago and I am not advocating L - but it seems L is now accepted by all major institutions and I must agree with the fact that L is much less prone to be mistaken with 1 then l is. It doesn't mean I like it :)


    Chemical calculators for labs and education
    BATE - pH calculations, titration curves
     
  14. Apr 6, 2005 #13
    I usually use "L" for liter, and "ml" for milliliter. When on a computer or on the Net where certain specific fonts are employed, I *HATE* to use "l" because it looks too much like "I".
     
  15. Apr 6, 2005 #14

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    I explained the reasoning with "l" vs."L".Capitals are used for physical quantities and multiples.Liter is not a part of the units which use capitals...I'm sorry for the French,but they're wrong.

    Daniel.
     
  16. Apr 7, 2005 #15

    Borek

    User Avatar

    Staff: Mentor

    m stands for mili and M for Mega - both are SI multiples.

    s stands for second, K for Kelvin - both are base SI units.

    So either I don't understand what you have written or you are not right :wink:

    What I am aiming at is that there are no 'hard' rules.

    And, while we can criticise units abbreviations defined by international organizations like IUPAC or CGPM we have no choice but to accept them (and to fight for changes if we think it is important) :smile:


    Chemical calculators for labs and education
    BATE - pH calculations, titration curves
     
  17. Apr 7, 2005 #16

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Sorry,i wasn't really precise.It happens from time time,i'm human,though.I may be wrog,occasionally.

    Daniel.
     
  18. Apr 13, 2005 #17
    Im sorry to bring this post up but I wanted to be sure that I was doing the redox equation right...

    [tex] Sn^{2+}_{(aq)} + Ag^{+}_{(aq)}\rightarrow Sn^{4+}_{(aq)}+Ag [/tex]

    was the equation (sorry for my typo earlier)

    And I needed to find the coeffecient on the left side of the equation (in front of tin and silver)... so..

    *tin has lost two electrons
    [tex] Sn^{2+}\rightarrow Sn^{4+}+ 2e^{-} [/tex]

    *silver has gained one electron (one atom of silver has gained one electron)
    [tex] Ag^{+} + e^{-}\rightarrow Ag [/tex]

    *2 electrons were lost by tin so to balance that I multiply Ag by 2...

    and the coeffecients are 1 in front of Sn and 2 in front of Ag? Is this right? TiA!
     
  19. Apr 13, 2005 #18

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Yes,it is correct...

    Daniel.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Molarity notation
  1. Molar mass (Replies: 7)

  2. Molar Ratios (Replies: 3)

  3. Molality and molarity (Replies: 2)

  4. Molar Enthalpy (Replies: 2)

  5. Molar Absorptivity (Replies: 1)

Loading...