Moles to Mass & Mass to Moles

Map

Mass A to Mol A to Mol B to Mass B

• Some questions will give you the amount of moles and ask to determine the mass
• converting moles to mass only requires on additional step.
• How many grams of Bauxite (Al2 O3) are required to produce 3.5 mol of pure Aluminum?

2 Al2O3 --> 4 Al + 3 O2

3.5 mol x 2/4 x 102/mol = 178.5 = 1.8 x 10^2 g of Al2O3

• How many grams of water are produced of 0.84 mol of Phosphoric Acid is completely neutralized by Barium Hydroxide?

2 H3PO4 + 3 Ba(OH)2 -> 6 HOH + Ba3(PO4)2

0.84 mol x 6/2 x 18/mol = 45.56 = 45 g of H2O

• How many gram of Silver nitrate are needed to produce 1.02 mol of silver chloride according to the reaction.

2 AgNO3 + BaCl2 -> Ba(NO3)2 + 2 AgCl

1.02 mol x 2/2 x 169.9/mol = 173 g

• How many moles of Lead(II) nitrate are consumed when 4.5 g of sodium sulfide completely reacts

Na2S + Pb(NO3)2 -> 2 NaNO3 + PbS

4.5 g x mol/78.1 x 1/1 = 0.058 mols of Pb(NO3)2