Nuclear chemistry question (1 Viewer)

[Munkiie]

I don't know how to do this question, please tell me what to do

Plutonium has a half life of 2.4 x 10^4 years. How long would we need to store a sample of plutonium for its activity to drop to less that 0.1% of its original value?

Thanks in advance!

 

[anomalousdecay]

Are you sure this is supposed to be 0.1%? Shouldn't it be something like 10% or 0.1 of the original value?

By the way, what level of maths do you do? If you do general maths, then you will have to learn the longer way of doing the question.

 

[golgo13]

To answer the question, i guess its easier to visualise this as a pie, so lets say it takes me 2.4x10^4 years to eat half the pie, now as i'm eating the pie i'm getting full so i'm only able to eat half the portion i ate before, and as i continue i'm getting more full so it means each time i'm eating it, i'm only eating half the amount previously every 2.4x10^4 years. So in numbers if 100% is my complete, after 2.4x10^4 years, i'm left with 50% then the following 2.4x10^4 years i'm left with 25%, the following 2.4x10^4 years i'm left with 12.5% and so on. This is quite a primitive way to think about it and it can be time consuming, there is the formula with exponential decay which should be applicable here as well i believe it is A=A0e^-kt, A being amount. A0 being original amount, k being decay constant and t being time.