Question

Calculate the number of moles of Cl atoms in 1.81×1024 formula units of magnesium chloride, MgCl2.Express your answer numerically in moles.

Answer 1

1) Convert the number of molecules into the number of Cl atoms

`Cl\text{ atoms=1.81}\cdot10^(24)moleculesofMgCl_2\cdot\frac{2\text{ atoms of Cl}}{1moleculeofMgCl_2}=3.62\cdot10^(24)\text{ Cl atoms}`

There are 3.62*10^24 Cl atoms in 1.81×10^24 of MgCl2.

2) Convert the number of Cl atoms into moles of Cl.

`\text{mol Cl=3.62}\cdot10^(24)\text{ Cl atoms}\cdot\frac{1\text{ mol Cl}}{6.022\cdot10^(23)\text{ Cl atoms}}=6.011\text{ mol Cl.}`

There is 6.011 mol Cl in 1.81×10^24 of MgCl2.