Today in chem. class, Mr. Doktor taught us an additional step from last class, which allows us to determine the mass from an amount of moles or vice versa. Following this chart will help you make the right conversions from “A” to “B”.
Example: How many grams of Bauxite (Al2O3) are required to produce 3.5 mol of pure aluminum?
The balanced chemical equation: 2Al2O3 = 4Al + 3O2
3.5mol * (2/4) * (102g/1mol) <- (molar mass) = 178.5 g = 1.8*10^2g
Example: How many grams of water are produced if 0.84 mol of Phosphoric Acid is completely neutralized by Barium Hydroxide?
The balanced chemical equation: 2H3PO4 + 3Ba(OH)2 = Ba3(PO4)2 + 6H2O
0.84mol * (6/2) * (18g/1mol) <- (molar mass) = 45g
There is no way to go from the mole of one substance to the mass of another directly.
YOU ALWAYS NEED TO CONVERT TO MOLES FIRST.
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