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Posted by on Saturday, December 10, 2011 at 11:49pm.

Tc-99 is a radioactive isotope that decays by beta emission and is used by radiologists in the diagnosis of liver disease. Its decay behavior is shown by the activity-time table. What is its half-life?

  • Chemistry - , Sunday, December 11, 2011 at 12:50am

    You are supposed to look at the table and use the data to calculate the half life. How do you suppose we can do that if you don't show the table?

  • Chemistry - , Sunday, December 11, 2011 at 10:29am

    The table wasn't available

  • Chemistry - , Sunday, December 11, 2011 at 10:32am

    counts/min time(hours)
    800 0
    713 1
    450 5
    200 12
    112 17
    a. 5h
    b. 6h
    c. 12h
    d. 99h

  • Chemistry - , Sunday, December 11, 2011 at 2:52pm

    ln(No/N) = kt
    No = 800 in all cases.
    N = values from table
    k = solve for this
    t = time in hours.
    For example, the first one is
    ln(800/713) = k(1 hour)
    k = 0.115 if I didn't goof.
    Do that for each time period and average the values. Then substitute into the following:
    k = 0.693/t1/2 and solve for t1/2.

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