To calculate the atomic mass of oxygen based on the given isotopes and their abundances, you can use the formula for weighted averages. The formula is:
\[ \text{Atomic Mass} = \sum (\text{mass of isotope} \times \text{abundance}) \]
First, express the abundances as fractions:
- For \(^{16}\text{O}\): 99.75% = 0.9975
- For \(^{17}\text{O}\): 0.037% = 0.00037
- For \(^{18}\text{O}\): 0.204% = 0.00204
Now, multiply the mass of each isotope by its abundance:
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For \(^{16}\text{O}\): \[ 15.995 , \text{amu} \times 0.9975 = 15.9550125 , \text{amu} \]
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For \(^{17}\text{O}\): \[ 16.995 , \text{amu} \times 0.00037 = 0.00628815 , \text{amu} \]
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For \(^{18}\text{O}\): \[ 17.999 , \text{amu} \times 0.00204 = 0.03673996 , \text{amu} \]
Now, add these contributions together:
\[ \text{Atomic Mass} = 15.9550125 + 0.00628815 + 0.03673996 = 15.99804061 , \text{amu} \]
Therefore, the atomic mass of oxygen, calculated from the given isotopes, is approximately:
\[ \boxed{15.998 , \text{amu}} \]
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