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January 25, 2015

January 25, 2015

Posted by **John** on Thursday, April 25, 2013 at 11:38am.

- A.P. Chemistry -
**DrBob222**, Thursday, April 25, 2013 at 2:20pmThe simple answer:

It will take 1.4E10 years.

If the half life is 1.4E10 and you want exactly 1/2 of the Th to decay, it will take just one half life. right?

You can work it out.

k = 0.693/t_{1/2}

ln(No/N) = kt.

No = 1.0 mg

N = 0.5 mg

k from above.

Solve for t.

You should obtain 1.4E10 years.

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