## Chemistry 9th Edition

Mass of $^{185}Re$= 185.0 amu
Let m be the molar mass of $^{185}Re$: $186.207 = 0.6206*186.956+(1-0.6206)m$ $m=\frac{186.207-0.6206*186.956}{(1-0.6206}=185.0$ amu