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Homework Help: Can someone please help me with this radiochemistry question please

  1. May 17, 2009 #1
    1. The problem statement, all variables and given/known data

    Calculate the radioactive concentration (MBq/ml) of a sodium pertechnetate [99mTC] solution with a concentration of 2.0 * 10^-6 g/L.

    Mr (sodium pertechnetate) = 186
    half life of [99mTc) = 6.02 hours
    Avagadro's constant = 6.02 * 10^23

    2. Relevant equations

    A= lamda N
    N = mNa/Mr

    3. The attempt at a solution

    Okay, so the first step would be to work out the decay constant (lamda) from the half life which I can do but, after that I kind of get stuck. Do I need to calculate the activity (A) by using the formula A= lamda N?
    How do I work out N if I don't have the mass to work out the moles of the compound? And then how does that enable me to work out the concentration using c=n/v without a volume

    Also, am I going about the question the correct way?
  2. jcsd
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