Question

a fictitious element X is composed of 25.0 percent of the isotope 48X, 20.0 percent of the isotope 49X and 55.0 percent of the isotope 50X. estimate the atomic mass of element X

Answer 1

Answer is: atomic mass of element X is 49.3.

ω(⁴⁸X) = 25.0% ÷ 100%.

ω(⁴⁸X) = 0.25.

Average atomic mass of element X =

Ar(⁴⁸X) · ω(⁴⁸X) + Ar(⁴⁹X) · ω(⁴⁹X) + Ar(⁵⁰X) · ω(⁵⁰X).

Average atomic mass of element X = 48 · 0.25 + 49 · 0.20 + 50 · 0.55.

Average atomic mass of element X = 12.0 + 9.80 + 27.5.

Average atomic mass of element X = 49.3.