Notices
Results 1 to 4 of 4

Thread: Barium Meal

  1. #1 Barium Meal 
    Forum Sophomore scientist-to-be's Avatar
    Join Date
    Apr 2007
    Location
    Cairo, Egypt
    Posts
    124
    In medical diagnosis, in order to detect stomach ulcers or imperfections in the digestion tract, Barium Sulphate is fed to the patients, since Barium sulphate is opaque to X-ray radiation. Barium ions are deposited on the walls of the alimentary canal, so X ray radiation is blocked and only allowed to penetrate in areas that have a damage or a lesion. Although Barium compounds are highly poisonous, it is said that Barium Sulphate is safe to ingest since it is very insoluble in water. But isn't there a considerable amount of HCl in the stomach? Wouldn't the hydrochloric acid react with barium sulphate, to form soluble products that can be absorbed and be very harmful to the body??


    In theory, there is no difference between theory and practice. In practice, however, there is.
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Freshman Keith's Avatar
    Join Date
    Mar 2007
    Location
    NY
    Posts
    88
    If the H<sup>+</sup>+Cl<sup>-</sup> can't find any free ions, there isn't going to be a reaction. Generally, if it isn't soluble in one polar substance, it won't be in another.


    http://img216.imageshack.us/img216/6164/thinghl2.jpg
    "We make our world significant by the courage of our questions and by the depth of our answers." -Carl Sagan
    Reply With Quote  
     

  4. #3  
    Forum Professor
    Join Date
    May 2005
    Posts
    1,893
    The pH of the stomach is around 2-3. You shouldn't have a problem with the acidity making the sulphate salts more soluble until you got down to a pH of less than 1.
    Reply With Quote  
     

  5. #4 Re: Barium Meal 
    Forum Freshman
    Join Date
    May 2007
    Posts
    19
    Quote Originally Posted by scientist-to-be
    In medical diagnosis, in order to detect stomach ulcers or imperfections in the digestion tract, Barium Sulphate is fed to the patients, since Barium sulphate is opaque to X-ray radiation. Barium ions are deposited on the walls of the alimentary canal, so X ray radiation is blocked and only allowed to penetrate in areas that have a damage or a lesion. Although Barium compounds are highly poisonous, it is said that Barium Sulphate is safe to ingest since it is very insoluble in water. But isn't there a considerable amount of HCl in the stomach? Wouldn't the hydrochloric acid react with barium sulphate, to form soluble products that can be absorbed and be very harmful to the body??
    BaSO4 + H+ <--> HSO4- + Ba++

    Keq = Ksp/Ka

    Ksp = BaSO4 solubility product = 1.5*10^(-10)

    Ka = HSO4- acid constant = 2*10^(-2)

    --> Keq = 1.5*10^(-10)/2*10^(-2) = 0.75*10^-8

    If C is the initial concentration of H+ ions, we have:

    [Ba++] = Sqrt(C*Keq)

    If the stomach has pH = 2, then C = 10^(-2) so:

    [Ba++] = Sqrt[10^(-2)*0.75*10^-8] ~ 0.87*10^(-5) mol/L ~

    ~ 10^(-5) mol/L --> 1.37 mg of Ba every 1L of HCl solution in the stomach.

    So it's much under toxicity level.
    Reply With Quote  
     

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
  •