# 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?

Sep 7, 2016

Thyroxine has a formula of ${C}_{15} {H}_{11} {I}_{4} N {O}_{4}$, and a molar mass of $776.86 \cdot g \cdot m o {l}^{-} 1$. Almost $10 \cdot g$ iodine are present in the sample. How many $m g$?
$\text{Moles of thyroxine}$ $=$ $\frac{15 \cdot g}{776.86 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.0193 \cdot m o l$
And thus $\text{mg of iodine}$ $=$ $0.0193 \cdot m o l \times 4 \times 126.9 \cdot g \cdot m o {l}^{-} 1 \times {10}^{3} \cdot m g \cdot {g}^{-} 1$ $=$ $9801 \cdot m g$.