January 25, 2011: Moles to Mass and Mass to Moles (Angelo)

Moles to Mass and Mass to Moles:
- some questions will give you an amount of moles and ask you to determine the mass
- converting moles to mass only requires one additional step

EXAMPLE:


1. How many grams of Bauxite (Al2O3) are required to produce 3.5 mols of pure Aluminum.

Create your balanced equation: 2NO3 -----> 4Al + 3O2
Create your equation: 3.5 mol (Al) * (2 mols (Al2O3) / 4 mols (Al)) * (102 grams (Al2O3) / 1 mol (Al2O3)) = ?
Calculate: 3.5 mol (Al) * (2 mols (Al2O3) / 4 mols (Al)) * (102 grams (Al2O3) / 1 mol (Al2O3)) = 1.8 x 10^2 grams


2. How many moles of Lead (II) Nitrate are consumed when 4.5 grams of Sodium Sulphide completely react?

Create your balanced equation: Pb(NO3)2 + Na2S -----> PbS + 2NaNO3
Create your equation: 4.5 grams * (1 mol / 78.1 g.) * (1 mol / 1 mol) = ?
Calculate: 4.5 grams * (1 mol / 78.1 g.) * (1 mol / 1 mol) = 0.058 grams