Calculate the number of moles of Cl atoms in 3.61×1024 formula units of magnesium chloride, MgCl2?

Answer 1

Hi there. If I understand your question correctly, you can simply divide the total number of formula units of the compound by Avogadro's number (6.02x10²³ formula units/mol). In this case, there are approximately 6 mols of magnesium chloride present in 3.61x10²⁴ formula units of magnesium chloride.

Answer 2

Since 1 mole = 6.02 x 10²⁴ particles (molecules, atoms, ions, etc.), and you have 2 atoms of Cl per formula unit in MgCl₂, And you are given that there are 3.61 x 10²⁴ formula units of the MgCl₂ then 2 times 3.61 x 10²⁴ will give you the answer.

Answer 3

The formula MgCl2 tells us that for every unit of MgCl2, there are 2 units of Cl. The way we express this numerically, where our units are moles (as specified by this problem), is with a ratio:

(2 mol Cl / 1 mol MgCl2) or (1 mol MgCl2 / 2 mol Cl)

Thus, for 3.61 x 10^24 moles of MgCl2, the calculation for moles of Cl is:

3.61 x 10^24 mol MgCl * (2 mol Cl / 1 mol MgCl2) = 7.22 x 10^24 mol of Cl

From a mathematical standpoint we are simply multiplying our given quantity by 2. But it’s good practice to pay attention to the units, so I included the units so you can see that the “mol MgCl2l” units divide out, and we are left with “mol Cl” as the units for our answer.