Question

How many grams are in .$0.02{\text{ }}moles$.of beryllium iodide,$Be{I_2}$?

Answer 1

Divide the mass of the substance in grams by its atomic weight. This will give you the quantity of moles of that substance that are in the predetermined mass. While dividing the two units that both use grams in their estimation the grams offset one another, leaving just the moles.

Complete step by step answer:
All you require to do here is to utilize a change factor that can take you from grams of beryllium iodide to moles of beryllium iodide. As you probably are aware, the molar mass of a compound tells you the mass of precisely $1{\text{ }}mole$ of that compound.
Beryllium iodide has a molar mass of $262.821{\text{ }}g{\text{ }}mo{l^{ - 1}}$, which implies that $1{\text{ }}mole$ of beryllium iodide has a mass of $262.821{\text{ }}g$.
So you can say that you have:
$262.821{\text{ }}g{\text{ }}mol - 1$ = $\dfrac{{262.821{\text{g}}}}{{1{\text{mole Be}}{{\text{I}}_2}}}$
To find the mass of 0.02 moles of beryllium iodide, simply multiply the number of moles by the molar mass in conversion factor form.
0.02{\text{ }}moles$$$$Be{I_2}$$$$* $\dfrac{{262.821{\text{g}}}}{{1{\text{mole Be}}{{\text{I}}_2}}}$ = $5g$

Note:
$1{\text{ }}mole{\text{ }} = {\text{ }}6.022{\text{ }}x{\text{ }}{10^{23}}$ particle or atoms or molecules or electrons or protons etc. The number of the constituent particles of atoms such as molecules or atoms or ions present in a given sample is related with the mass of the substance present in the sample using Avogadro’s number. The SI unit of Avogadro’s number is inverse of mole i.e. $mol{e^{ - 1}}$
The molecular weight is how much each molecule of the substance weighs and is given in grams over moles. The weight for any atom is on a periodical table under that listing of atoms.