The Chemistry Book

Lesson: 102
Unit: 3
State Content Standard: 3.d.

Lesson Title: Molar Mass(Gram Formula Mass)
Textbook page: 165-168, 183
Chemistry Passport: Page 116

Objectives

• Students should be able to calculate molar mass from the formula unit or the provided name.
• Students should know the definition of molar mass.

Chemists define molar mass as the mass of one mole of a substance. The units for molar mass are g/mol or g mol^-1. Biochemists may use the unit dalton, Da, for molar mass.

Steps:

1. Build a simple table
2. List the atoms in the molecule
3. Count the atoms of each element
4. Add the mass of each element
5. Multiply the number of atoms by the respective atomic masses
6. Add up the different masses for the elements
7. Round to the proper significant figures

For Example:

1. Water = H2O
2. H2 + O
3. 2(1.01) + 1(16.00)
4. 18.02 g/mol

References

Chemistry textbook pgs. 165-168, 183 http://www.cde.ca.gov/ta/tg/sr/documents/rtqchem.pdf (if you want to have any practice with these questions)