Question

The hormone, thyroxine is secreted by the thyroid gland, and has the formula `C_15H_17NO_4I_4`. How many milligrams of iodine can be extracted from 15.0 grams of thyroxine?

Answer 1

Thyroxine has a formula of `C_15H_11I_4NO_4`, and a molar mass of `776.86*g*mol^-1`. Almost `10*g` iodine are present in the sample. How many `mg`?

Explanation:

`"Moles of thyroxine"` `=` `(15*g)/(776.86 *g*mol^-1)` `=` `0.0193*mol`

And thus `"mg of iodine"` `=` `0.0193*molxx4xx126.9*g*mol^-1xx10^3*mg*g^-1` `=` `9801*mg`.

Iodine is a massive element, and thus provides most of the mass in a given sample.