Question

An imaginary atom X has two isotopes. If the isotopes have atomic masses of 54.1 ( abundance 54%) and 55.1 then calculate the atomic mass of the atom X.

Answer 1

Answer:

$\footnotesize\longrightarrow \sf Average \: Atomic \: mass = \dfrac{\sum \: \%age \: of \: each \: isotope \times Atomic \: mass}{100}$

• Isotope (I) Atomic mass = 54.1
• %age abundance of Isotope (I) = 54%
• Isotope (II) Atomic mass = 55.1
• %age abundance of Isotope (II) = 100 - 54 = 46%

$\footnotesize\longrightarrow \sf Average \: Atomic \: mass = \dfrac{54 \times 54.1 + 46 \times 55.1}{100}$

$\footnotesize\longrightarrow \sf Average \: Atomic \: mass = \dfrac{2921.4 + 2534.6}{100}$

$\footnotesize\longrightarrow \sf Average \: Atomic \: mass = \dfrac{5456}{100}$

$\footnotesize\longrightarrow \underline{ \boxed{ \red{\bf Average \: Atomic \: mass =54.56 \: amu}}}$

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