mCi or µCi into grams

Disscussing old, rare, very specific or otherwise uncommon units and measurements
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mCi or µCi into grams

Postby napoleon dynamite » Thu Jun 30, 2005 3:42 am

Hello, could someone please tell me how many units i would need,
if i wanted 1 gram of each of the substances below.

Methyltrienolone, [17 á-methyl-3H]-, 1mCi (37MBq)
NET590001MC Unit size: 1 mCi

Methyltrienolone, [17 á-methyl-3H]-, 250µCi (9.25MBq)
NET590250UC Unit size : 250 µCi

napoleon dynamite

You need to know the half-life

Postby Guest » Tue Aug 16, 2005 9:03 pm

The unit Bq and Ci are Bequerel and Curie, Units of radiation. They are can also used to determine the mass/quantity of radioactive substance you have.

dN/dt = (lambda)N

radioactivity=decay constant*number of undecayed atoms

a radioactivity of Bq is one decay per second. If you know the half-life the decay constant is calculated from:

t(1/2) = ln 2 / (lambda)

Then devide the Bq rating by lambda to obtain N, the number of undecayed atoms in the sample.

Devide N by Avagadro's number 6.02x10^23 to get the number of moles of substance you have, then multiply it by its molecular weight.

This will give you the mass.

Now that you know the number of grams in one unit, you can order the correct number of units.

Or alternatively, order one unit, then weigh it!



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