Chemistry – Stoichiometry - Relative masses of atoms and molecules | e-Consult
Stoichiometry - Relative masses of atoms and molecules (1 questions)
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To calculate the relative atomic mass (Ar) of element X, we use the following formula:
Ar = (Mass of isotope 1 x Relative abundance of isotope 1) + (Mass of isotope 2 x Relative abundance of isotope 2)
In this case:
- Mass of isotope 1 (20X) = 20 amu
- Relative abundance of isotope 1 = 60% = 0.60
- Mass of isotope 2 (22X) = 22 amu
- Relative abundance of isotope 2 = 40% = 0.40
Therefore:
Ar = (20 x 0.60) + (22 x 0.40) = 12 + 8.8 = 20.8 amu
So, the relative atomic mass of element X is 20.8.