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Number of beta particles emitted per second by dose of 131I

Submitted by mychemistry on Mon, 05/09/2011 - 17:02

This is the second part of the problem so i mention here part a first

the isotope 131I has a half life of 8.07 days and undergoes beta decay with an energy of 9.36 x 10^7 kj/mol.If a patiet with a thyroid disorder is given this isotope and 7.45 pg is incorporated into thyroid gland, how much energy will the gland recieve in one day?
this is 4.4 x 106-4 J and i know how to calculate this
but i want help with part b which is

how many beta particles are emitted per second by the dose of 131I
and the answer is 3.41 x 1064 beta/sec ..but i don't know how to get this answer


If you know the mass of 131I that decays, you can calculate the number of beta particles emitted.
Each atom releases 1 beta particle
Each mole of atoms (6.02 x 10^23 atoms) or 131g will emit 6.02 x 10^23 beta particles.