Page 235 - Chemistry eBook

Gram Formula Mass / Gram Molecular Mass / Gram Atomic Mass Problems
• These are 3 names for this type of equation. They all have the word mass in them.
• The questions on this topic will ask you to find the mass / number of grams of a molecule.
Find the atomic mass of Na2CO3.
• The simplest way to find the total mass is to make a chart:
1. Column 1 lists the elements.
2. Column 2 lists the number of atoms of the
element (coefficient × subscript).
3. Column 3 lists the mass of the element (see
Reffy, Periodic Table).
4. Column 4: Multiply number of atoms ×
mass. Then add together the total masses of all the elements.
There are many Regents questions on this topic.
Element
Number of Atoms (Coefficient × subscript)
Mass of Each Atom
Total Mass of Element (Number of Atoms × Mass)
Na
2
23
46
C
1
12
12
O
3
16
48
Total Mass of All Elements 106 grams
UNIT 6: MATH IN CHEMISTRY © 234