Naturally occurring iodine has an atomic mass of 126.9045. A 12.3849 -g sample of iodine is accidentally contaminated with 1.00070 g of ^129 I, a synthetic radioisotope of iodine used in the treatment of certain diseases of the thyroid gland. The mass of ^129 I is 128.9050amu.

Find the apparent "atomic mass" of the contaminated iodine.

5 answers

avg atomic mass=
1.00070*128.9050 +(12.3849-1.00070)126.9045

oops, all that has to be divided by the total mass, 12.3849 g

567.0

127.055 amu