Question

There are three naturally occurring isotopes of magnesium with given abundances. Calculate the weight of "naturally" occurring magnesium in this weird parallel universe in g/mol.

Answer 1

To calculate the average mass of a Mg atom, multiply the percent abundance of each isotope by its mass and then sum up the products to get the average mass.

Step-by-step explanation:

To calculate the average mass of a Mg atom, you need to use the percent abundances and the mass of each isotope. Multiply the percent abundance of each isotope by its mass and then sum up the products to get the average mass.

1. Calculate the mass contribution of each isotope by multiplying the percent abundance by the mass of the isotope. For 24Mg, (78.70%)*(23.98 amu) = 18.89 amu. For 25Mg, (10.13%)*(24.99 amu) = 2.53 amu. For 26Mg, (11.17%)*(25.98 amu) = 2.90 amu.
2. Add up the mass contributions from each isotope to get the average mass: 18.89 amu + 2.53 amu + 2.90 amu = 24.32 amu.

Therefore, the average mass of a Mg atom is 24.32 amu.