Notices
Results 1 to 4 of 4

Thread: a comparison between an experimental pH and a calculated pH

  1. #1 a comparison between an experimental pH and a calculated pH 
    Forum Freshman
    Join Date
    Oct 2013
    Posts
    13
    hello everyone
    i have a lab of solvay process, among some réactions, i have this one

    NH3(aq) + H2O(aq) + NaCl(s) -----> NH4+(aq) + OH(aq) + Na+,Cl(aq)

    they asked me to do a comparison between an experimental pH and a calculated pH.
    the experimental pH = 12,5
    the calculated pH = 15,7 ( i calculated by the concentration of ammniac which is 15 mol/L)

    so what can say? i though about the presence of the sel NaCl but it's pH is 7 i guess so it dosen't effect the pH of the solution, so why the experimental pH is lower than the calculated one?
    please help me , it's so important


    Reply With Quote  
     

  2.  
     

  3. #2  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,422
    Hint: Is this reaction is an equlibrium? If so not all of the ammonia will be protonated by water, so there is not a 100% yield of OH-

    Also at such high concentrations you should be considering activities not concentrations. At work I use this model to calculate them.


    Reply With Quote  
     

  4. #3  
    Forum Freshman
    Join Date
    Oct 2013
    Posts
    13
    yes it is, so it's simply this because not all of the ammonia did be protonated by water?
    Reply With Quote  
     

  5. #4  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,422
    That would be the simple answer, I'm guessing the activities not being unity at such a high molality (15 mol/L) may also have an effect but I can't be bothered to run the model (I have to do enough of that at work )
    Reply With Quote  
     

Similar Threads

  1. Replies: 13
    Last Post: May 29th, 2013, 06:14 AM
  2. How is the age of the universe calculated???
    By rohandesilva in forum Physics
    Replies: 47
    Last Post: September 28th, 2012, 09:39 AM
  3. Forensic Voice Comparison
    By stander-j in forum Criminology and Forensic Science
    Replies: 2
    Last Post: September 15th, 2012, 03:52 PM
  4. how can the mass of a black hole be calculated?
    By brane wave in forum Astronomy & Cosmology
    Replies: 25
    Last Post: September 15th, 2011, 12:19 PM
  5. Search comparison
    By rdx65 in forum Computer Science
    Replies: 1
    Last Post: December 2nd, 2010, 09:02 AM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •