Chromium and other metals with metallic bonding do not literally have "moles" but rather "formula units" with similar properties. The formula unit is a single atom; therefore, the number of atoms in 3 formula units is 3 times Avogadro's Number or about 1.81 X 1024 atoms.
1 formula unit of aluminum sulfate has the formula Al2(SO4)3. So there are 2 atoms of aluminum, 3 atoms of sulfur and 12 atoms of oxygen in 1 formula unit of aluminum sulfate. There are no molecules of aluminum sulfate. They are called formula units.
Assuming that the number "9.871023" would or should have been written as "9.87 X 1023" if the typographical resources to do so were available to the questioner: Avogadro's Number, which is the number of formula units in a mole of any material, is about 6.022 X 1023. The gram formula mass for aluminum oxide is 101.96. Therefore, the mass of the stated number of formula units of aluminum oxide is: 101.96(9.87/6.022) or about 164 grams, to the justified number of significant digits.
One mole of formula units = 6.022 x 1023 formula units.
The chemical equation is Al2(SO4)3 + 3BaCl2 --> 2AlCl3 + 3BaSO4. (I corrected the formulas containing aluminum.)
Aluminum sulfide is Al2S3, which has 3 sulfur atoms per formula unit. 1.10mol means 1.10(6.02x1023), which is 6.62x1023 formula units. Multiple that by 3 to get your sulfur atoms: 6.62x1023(3) = 1.99x1024 sulfur atoms.
define the following write the units and formula
5.68 mol MgO x 6.02E23 formula units / 1 mol = 3.42E24 Formula Units
The atomic mass for Aluminum is 26.98 atomic mass units or amu.
10 formula units
kCl has more formula units