Question

Find the average atomic mass for Mg if 78.99% of Mg atoms are 24Mg with a mass of 23.9850419 amu, 10.00% are 25Mg with a mass of 24.9858370 amu, and 11.01% are 26Mg with a mass of 25.9825930 amu. (Round to three decimal places)

a. 24.305 amu
b. 25.305 amu
c. 24.915 amu
d. 24.985 amu

Answer 1

To calculate the average atomic mass of Mg, you need to multiply the mass of each isotope by its percent abundance and then add up the results. For Mg, we have three isotopes: 24Mg, 25Mg, and 26Mg.

Step-by-step explanation:

To calculate the average atomic mass of Mg, you need to multiply the mass of each isotope by its percent abundance and then add up the results. For Mg, we have three isotopes: 24Mg, 25Mg, and 26Mg. The percent abundances provided are 78.99%, 10.00%, and 11.01% respectively. The corresponding masses for each isotope are 23.9850419 amu, 24.9858370 amu, and 25.9825930 amu. Using these values, we can calculate the average atomic mass as follows:

1. (0.7899 * 23.9850419) + (0.1000 * 24.9858370) + (0.1101 * 25.9825930)
2. (18.9283576239) + (2.4985837) + (2.877821963)
3. 24.304763A

Rounded to three decimal places, the average atomic mass for Mg is 24.305 amu.