Cobalt Decay
Stage: 5 Challenge Level:

Do you think it will be easy to distinguish between each of the
isotopes of cobalt?
Imagine to start that that the sample consists of a single isotope
of the cobalt. Would such a sample have too much or too little
cobalt at each of the times indicated? How could you adjust the
sample to bring the sample in line with the numbers
indicated?
This problem makes use of
chemistry concepts found in A-level. The main fact of importance is
that in each half-life half of the cobalt will transform into other
matter, the vast majority of which will remain in the sample.
Mathematically, you will need to use linear algebra, simultaneous
equations such as typically encountered at post-16 level,
although a simpler numerical analysis will allow younger students
to engage with the problem.
Published November 2009,December 2009.