Question

A certain element X has four isotopes. 4.350% of X has a mass of 49.94605 amu. 83.79% of X has a mass of 51.94051 amu. 9.500% of X has a mass of 52.94065 amu. 2.360% of X has a mass of 53.93888 amu. What is the average atomic mass of element X?

Answer 1

Answer: The average atomic mass of the element X is 51.99592 amu

Explanation:

Mass of isotope 1 = 49.94605 amu

% abundance of isotope 1 = 4.350% = $\frac{4.350}{100}=0.0435$

Mass of isotope 2 = 51.94051 amu.

% abundance of isotope 2 = 83.79% = $\frac{83.79}{100}=0.8379$

Mass of isotope 3 = 52.94065 amu.

% abundance of isotope 2 = 9.500% = $\frac{9.500}{100}=0.095$

Mass of isotope 4 = 53.93888 amu.

% abundance of isotope 2 = 2.360% = $\frac{2.360}{100}=0.0236$

Formula used for average atomic mass of an element :

$\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})$

$A=(49.94605\times 0.0435)+(51.94051 \times 0.8379)+ (52.94065\times 0.095)+(53.93888\times 0.0236)$

$A=51.99592amu$

Therefore, the average atomic mass of the element X is 51.99592 amu