Respuesta :
Answer: Relative atomic mass of the element is 63.6 amu.
Explanation: We are given an element having 2 peaks in the mass spectrum, which means that the masses of two isotopes of an element are given.
m/z value of isotope 1 or mass of isotope 1 = 63amu
m/z value of isotope 2 or mass of isotope 2 = 65amu
Fractional abundance of the isotopes can be calculated as:
[tex]\text{Fractional abundance}=\frac{\%\text{ abundance}}{100}[/tex]
Fractional abundance of isotope 1 = [tex]\frac{69.1}{100}=0.691[/tex]
Fractional abundance of isotope 2 = [tex]\frac{30.9}{100}=0.309[/tex]
To calculate average atomic mass of an element, we use the formula:
[tex]\text{Average atomic mass}=\sum_{i=1}^n(\text{Mass Number})_i\times (\text{Fractional Abundance})_i[/tex]
Now, putting the values of abundances and mass numbers of 2 isotopes in above equation, we get
[tex]\text{Average atomic mass}=(63\times 0.691)+(65\times 0.309)[/tex]
Average Atomic Mass of given element = 63.618 amu
Converting this into 3 significant figures, we get
Average atomic mass = 63.6 amu
