question_answer 40)

Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes: Isotope Isotopic molar mass Abundance \[{{\,}^{36}}Ar\] 35.96755 g \[mo{{l}^{-1}}\] 0.337% \[{{\,}^{38}}Ar\] 37.96272 g \[mo{{l}^{-1}}\] 0.063% \[{{\,}^{40}}Ar\] 39.9624 g \[mo{{l}^{-1}}\] 99.6%  

Answer:

Average atomic mass of Argon \[\text{= }\!\!\Sigma\!\!\text{ }\frac{\text{ }\!\!%\!\!\text{ abundance}}{\text{100}}\text{ }\!\!\times\!\!\text{ Isotopic}\,\text{molar}\,\text{mass}\] \[=\left[ \frac{0.337}{100}\times 35.96755 \right]+\left[ \frac{0.063}{100}\times 37.96272 \right]+\] \[\left[ \frac{99.6}{100}\times 39.9624 \right]\] \[=0.1212+0.0239+39.80255\] \[=39.94765\text{ }g\,\,mo{{l}^{-1}}\]