1. Not finding help here? Sign up for a free 30min 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!

Redox Relapse

  1. May 18, 2005 #1
    We need to know what the products of KI + H2O in ionic form.
     
  2. jcsd
  3. May 18, 2005 #2

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    The reaction should be

    [tex] 2KI+H_{2}O\rightleftharpoons K_{2}O+2HI [/tex]

    which in ionic form

    [tex] 2K^{+}+2I^{-}+H^{+}+OH^{-}\rightleftharpoons 2K^{+}+O^{2-}+2H^{+}+2I^{-} [/tex]

    I don't see any redox here...

    Daniel.
     
  4. May 18, 2005 #3
    THe labis on oxidation reduction. It says that ppt turns pink in the presence of hyrdroxide ions and the starch will turn black/blue in the presence of molecular iodine. We figured that this meant that in the equation that this meant in the products their will be a hydroxide ions and an I molecule. We thought that the answer you gave us was right but our teacher said that we were closer when we showed him KI + H2O--> OH + K + I2 + H
     
  5. May 18, 2005 #4

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Yes,i didn't think of that option.There it is.Can u find the coefficients by accomplishing the electron transfer ?

    [tex] aK^{+}+bI^{-}+cH^{+}+dOH^{-}\rightleftharpoons eK^{+}+fOH^{-}+gI_{2}+h H_{2}\uparrow [/tex]

    Daniel.
     
  6. May 18, 2005 #5
    yeah we should be able to, um what are the a,b,c,d,e,f,g for?
     
  7. May 18, 2005 #6

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Coefficents,like 1,2,1/2,3/2,3.

    So who's getting oxidated and who's getting reduced...?

    Daniel.
     
  8. May 18, 2005 #7
    umm I havent done it yet;P
     
  9. May 18, 2005 #8

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    It's not funny.If u haven't done redox reactions in school,why do you bother with this problem...?:rolleyes:

    Daniel.
     
  10. May 18, 2005 #9
    Me thinks something is a miss here. Was it hydroxide or peroxide ?
     
  11. May 18, 2005 #10
    it was hydroxide
     
  12. May 19, 2005 #11
    OK what is ppt ?
     
  13. May 19, 2005 #12

    Borek

    User Avatar

    Staff: Mentor

  14. May 22, 2005 #13
    the ppt is phenalthailene...and the reaction is K + I + H2O --> KOH + I + H
     
  15. May 23, 2005 #14

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    Alright, I would imagine that this is a simple dissociation reaction, [tex]KI_{(s)}+H_2O \rightarrow K^{+}_{(aq)}+I^{-}_{(aq)} [/tex]

    The starch test will not work without molecular iodide however, I2. You'll need both I2 and I-, for the iodine complex involving I3-.
     
  16. May 24, 2005 #15
    OK I'm highly dyslexic, but did you mean phenolphthalein ? There still is something a miss here (like what would oxidize the I-).
     
  17. May 24, 2005 #16

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    potassium reacts with water??? Never actually encountered this before, I though it would be a spectator ion. I've read about this and it seems that KI is dissolved in water to provide I-, subsequently I2 is added to form I3-, which can form complexes with starch conterparts to form a colored solution.

    I'm somewhat sensitive about the way some high schools deal with redox reactions as at times they are completely misleading and inaccurate. I've had a post in my forum a couple of months ago regarding a high school chemistry competition of which one of the answers provided turned out to be completely inaccurate. I couple of students decided to seek help online for references and quotes.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Redox Relapse
  1. Redox paradox (Replies: 3)

  2. Redox reactions (Replies: 0)

  3. Redox reactions (Replies: 3)

  4. Redox Reaction (Replies: 4)

Loading...