The atomic weight of Ga is 69.72 amu. There are only two naturally occurring isotopes of gallium: $^{69} G a$ $"^69Ga$ with a weight of 69.0 amu, and $^{71} G a$ $"^71Ga$ with a weight of 71.0 amu. What is approximate natural abundance of the $^{71} G a$ $"^71Ga$ isotope?

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Answer 1 · 2017-06-06T07:58:10

The natural abundance is $= 36 %$ $=36%$

Let the percentage of the isotope $^{71} G a$ $""^71Ga$ be $= x %$ $=x%$

Then,

The percentage of the isotope $^{69} G a$ $""^69Ga$ is $= (100 - x) %$ $=(100-x)%$

We write the mass balance equation

$100 \cdot 69.72 = x \cdot 71 + (100 - x) \cdot 69$ $100*69.72=x*71+(100-x)*69$

$6972 = 71 x + 6900 - 69 x$ $6972=71x+6900-69x$

$2 x = 6972 - 6900 = 72$ $2x=6972-6900=72$

$x = 36$ $x=36$

Therefore,

The percentage of the isotope $^{71} G a$ $""^71Ga$ is $= 36 %$ $=36%$

The atomic weight of Ga is 69.72 amu. There are only two naturally occurring isotopes of gallium: 69Ga"^69Ga with a weight of 69.0 amu, and 71Ga"^71Ga with a weight of 71.0 amu. What is approximate natural abundance of the 71Ga"^71Ga isotope?