Chemistry: Atoms First (2nd Edition)

The mass of $^{185}Re$ is equal to 185 u.
1. The sum of all abundances must be equal to 100$\$$(1):$$x+0.6260 = 1x = 1 0.6260 x = 0.3740 $$2. Calculate the missing atomic mass:$$( 0.3740 )( x )+( 0.6260 )( 186.956 \space u)=186.207 \space u ( 0.6260 )(x) = 186.207 \space u -( 0.6260 )( 186.956 \space u) x = \frac{186.207\space u - ( 0.6260 )( 186.956 \space u)}{0.3740 } x = 185 \space u$\$