Posted by Mary on Saturday, February 9, 2008 at 7:49pm.
A Cesium 137 sample has a measured radioactivity of 50 microcuries.Cesium 137 has a halflife of 30 years.
How long will it take this sample to be reduced to a residual radioactivity of 6.25 microcuries?
Is there a formula to calculate half life?

Chemistry please help!  DrBob222, Saturday, February 9, 2008 at 9:01pm
k = 0.693/t_{1/2}
Then ln(No/N) = kt
No = 50 microcuries
N = 6.25 microcuries
k from above (t1/2 = 30 years).
t = solve for this.

Chemistry please help!  Anonymous, Wednesday, February 25, 2015 at 2:44pm
A 45 gram sample of a substance that's used to preserve fruit and vegetables has a kvalue of 0.1109.
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