To calculate the gram molecular weight of a substance made up of more than one element (compound), we add up the atomic weights of the elements that comprised the compound. Atomic weight are listed in most periodic tables.
Example Ca(NO3)2
Element
Number of Atoms
Atomic Weight
Total weight
Ca
1
40.08
40.08
N
2
14.01
28.02
O
6
16.00
96.00
Gram Molecular weight ( Molar Mass ) ; 1 mole =
166.10 g
If the compound is a hydrate (containing water) then the mass of the water molecules is added to the weight of the other atoms.
Assignment #1: Calculations of Molar Mass
Calculate the gram molecular weight (molar mass) of the following compounds. Use the atomic weights listed in the following periodic table
Formula
Molar Mass
K3PO4
(NH4)2SO4
CuCO3
P4O6
Na3PO4 *10 H2O
CO2
Pb(CH3COO)2
MnO2
Al(OH)3
TiCl4
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