Answer
2319.698 g
Procedure
Use the Avogadro's number and then the molecular weight to convert into grams. The formula for aluminum bromide is AlBr₃.
[tex]5.238\times10^{24}\text{ molecules AlBr}_3\frac{1\text{ mole}}{6.022\times10^{23}}\frac{266.69\text{ g}}{1\text{ mole}}=2319.698\text{ grams}[/tex]