Sodium only has one naturally occurring isotope, 23Na, with a relative atomic mass of 22.9898 u. A synthetic l, radioactive isotope of sodium, 22Na, is used in positron emission tomography. 22Na has a relative atomic mass of 21.9944 u. A 2.0878 g sample of sodium containing a mixture of 23Na and 22Na has an apparent “atomic mass” of 22.9665 u. Find the mass of 22Na contained in this sample.
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Expert's answer
2019-10-17T07:29:26-0400
Let x to be fractional abundance of "^{23}Na"
Let 1-x to be fractional abundance of "^{22}Na"
Then
"22.9898x + 21.9944 (1-x) = 22.9665"
"x= 0.9766"
m("^{23}Na" )= "2.0878\\times x =2.0878\\times0.9766 = 2.0389 g"
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