Answer:
The answer to your question is below
Explanation:
Data
Atomic mass Abundance
Mg -24 = 23.9850 79%
Mg -25 = 24.9858 10%
Mg - 26= ? ?
Process
1.- Find the abundance of Mg-26
The sum of the abundance of the three isotopes equals 100%
Abundance Mg-24 + Abundance-Mg-25 + Abundance-26 = 100
79 + 10 + Abundance-26 = 100
Abundance Mg-26 = 100 -89
Abundance Mg-26 = 11%
2.- Find the atomic mass of Mg-26, the average atomic mass is 24.31 amu
Average atomic mass = (abundance)(atomic mass- 24) + (abundance)
(atomic mass-25) + (abundance)(atomic mass-26)
24.31 = (0.79)(23.9850)+ (0.10)(24.9858) + (Atomic mass-26)(0.11)
24.31 = 18.94815 + 2.4986 + 0.11(atomic mass-26)
24.31 = 21.4342 + 0.11(atomic mass- 26)
0.11(atomic mass-26) = 24.31 - 21.4342
0.11(atomic mass-26) = 2.8758
Atomic mass-26 = 2.8758/0.11
<u> Atomic mass-26 = 26.1436 amu</u>
