Question

Determine the mass in grams of 3.06x10^21 atoms of arsenic.

Answer 1

To determine the mass of the number of atoms, the first step is to convert this number of atoms to moles using Avogadro's number:

$3.06\times10^{21}atoms\cdot\frac{1molAs}{6.022\times10^{22}atoms}=0.051molAs$

Convert this amount of moles to grams using the molecular weight of Arsenic:

$0.051molAs\cdot\frac{74.9g}{1molAs}=3.8199g$

It means that the answer is 3.8199g.