The element gallium has an atomic weight of 69.7 and consists of two stable isotopes gallium - 69 and gallium - 71. The isotope gallium - 69 has a mass of 68.9 amu and a percent natural abundance of 60.4 %. The isotope gallium - 71 has a percent natural abundance of 39.6%. What is the mass of gallium - 71?

The answer to your question is Gallium-71 = 70.9202 amu

Explanation:

Gallium atomic weight = 69.7

Gallium-69 = 68.9 amu abundance = 60.4%

Gallium-71 = x abundance = 39.6%

To solve this problem just write an equation and solve it for the mass of gallium-71.

Equation

Gallium = Gallium-69 (abundance) + Gallium-71 (abundance)

Substitution

69.7 = (68.9) (0.604) + Gallium-71 (0.396)

69.7 = 41.6156 + Gallium-71 (0.396)

Gallium-71 (0.396) = 69.7 - 41.6156

Gallium-71 (0.396) = 28.0844

Gallium-71 = 28.0844/0.396

Gallium-71 = 70.9202 amu