Notices
Results 1 to 3 of 3

Thread: Radioactivity 1

  1. #1 Radioactivity 1 
    Forum Masters Degree thyristor's Avatar
    Join Date
    Feb 2008
    Location
    Sweden
    Posts
    542
    Hi!
    I would be grateful if somebody could help me with this:
    "A piece of Am-241 has a radioactivity of 10kBq. Determine how much Am-241 it contains."
    Attempt at a solution:
    Let A be the activity
    Let N be the number of atoms
    We know that We can set our initial time to zero, which gives us .
    Furthermore, we know that A(t)=-N(t). We also know that . Now we use that one atom weights 241,0568229u and that the half-life is 432,2 y (I converted it to seconds). Then we get that the mass of our "piece" is approximately 78,7 micrograms. However, in the key it says 1,83 ng.
    What am I doing wrong here?


    373 13231-mbm-13231 373
    Reply With Quote  
     

  2.  
     

  3. #2  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,168
    When you converted to seconds did you inadvertently multiply by 432.2 twice?


    Reply With Quote  
     

  4. #3  
    Forum Masters Degree thyristor's Avatar
    Join Date
    Feb 2008
    Location
    Sweden
    Posts
    542
    No, I'm afraid I didn't.
    373 13231-mbm-13231 373
    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
  •