Post a New Question

chemistry

posted by .

If the radiicativr decay of nuclear explosion contains 90 Sr , with a half life of 28.1 years how long will it take for 99 of this radioaioot to decay

  • chemistry -

    99 what? 99 grams? 99 tons? 99%. I suspect 99%.
    Two steps. First determine k.
    k = 0.693/t1/2 and substitute into the following:
    ln(No/N) = kt
    I would set No = 100 if that is 99%.
    Then N = 1% (if 99% is gone)
    k from above
    Solve for t in years.

  • chemistry -

    Sorry don't understand it is 99 percent

  • chemistry -

    Ln(100)/1)=(0.693/t^1/2)(t). ??? Don't get it

  • chemistry -

    There isn't anything to get. Can you punch the calculator? That's all there is to it. Do it in steps. Don't try to muddle it up by putting all of it together.
    ln 100/1 = 4.605
    0.693/28.1 = 0.02466 = k
    so
    ln(100/1) = 0.02466*t
    4.605 = 0.02466t
    and t = 4.605/0.02466 = ? or about 200 years more or less.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. DrBob222

    On Monday you helped me to understand and answer the one question, but I am not too sure if they want all the calculations that you answered... regretably, I am still a bit lost with these! Below is the question as it is printed: The …
  2. physics

    A building has become accidentally contaminated with radioactivity. THe longest lived material in the building is strontium-90 (atomic mass of 90 Sr 38 is 89.9077). If the building initially contained 5.0kg of this subtstance and the …
  3. chemistry

    If there are 80 milligrams of a radioactive element decays to 10 milligrams in 30 minutes then what is the elements half life in minutes?
  4. chemistry

    The isotype caesium -137, which has a half life of 30 years, is a product of nuclear power plants. How long will it take for the amount of this isotype in a sample of caesium to decay to one-sixteenth of its original amount?
  5. chemistry

    How long will it take for 25% of the C-14 atoms in a sample of C-14 to decay?
  6. chemistry

    With a half-life of 14.3 years, how long will it take for100 g of phosphorus32 to decay to 12.5 mg?
  7. Physic

    A radioactive element x has half life of 30 days and will decay to become another new element Y.. a) calculate decay constant b) how long it will take for 90% of the no.Of atom in radioisotope x to decay?
  8. Physic

    A radioactive element x has half life of 30 days and will decay to become another new element Y.. a) calculate decay constant b) how long it will take for 90% of the no.Of atom in radioisotope x to decay?
  9. Physic

    A radioactive element x has half life of 30 days and will decay to become another new element Y.. a) calculate decay constant b) how long it will take for 90% of the no.Of atom in radioisotope x to decay?
  10. Forensics

    Strontium-90 is a radioactive waste product from nuclear reactors. It has a half life of 29 years. How many years would it take for a quantity of strontium-90 to decay 1/16 of its original mass?

More Similar Questions

Post a New Question