[truebites]

Hey,
a new member here.

I am doing an experiment in which I am determining the concentration of calcium in chalk. First off, I don't know what kind of chalk to use. The regular blackboard chalk, the sidewalk chalks or some other kinds? I am thinking of titrating the chalk solution with the known concentration of EDTA. However, how do I calculate % calcium in chalk?
Also, I need to know the actual % calcium in the said chalk to compare the experimental result with the true value. How can I know the true value?
I guess I could contact the manufacturers, but don't know what companies manufacture chalks. (By the way, if I buy a pack of chalk, does the cover of the chalk box mention % calcium concentration?)
I haven't found any such experiments in google either.
thanks in advance