Molar Mass
Objectives:
 Calculate moles, grams, and atoms/molecules using molar mass and
Avogadro’s Number
Analogy: Counting by Weighing
The empty box has a mass of 213 g
The box with the nails has a mass of 1340 g
The weight of one nail is 0.450 g
Set up & solve the factor label problem to determine the number of nails in the box.
molar mass-mass of 1 mole (6.02 x 1023 atoms) of any element
Definition 2a- 1 mole of an element has a mass equal to the mass number from the
periodic table in grams
Lithium= 6.9 grams
Carbon= 12.0 grams
Mercury= 200.6 grams
Phosphorus= 31.0 grams
Definition 2b- 1 mole of a compound has a mass equal to the SUM of the mass
numbers of the atoms in the formula from the periodic table in grams
H 2O
subscript- apply to the single atom to the left of the subscript
molar mass- 18.0 grams
(NH4)2SO4
parentheses- multiply the subscript outside and the subscript inside
molar mass= 132.1 grams
How can I use factor-label to explain the mole?
T. O’Toole
Identities for Factor Label:
1 mole
Periodic Table grams
Periodic Table grams
1 mole
Ex: How many moles are in 2223 grams of C 12H22O11?
molar mass=
342.0 grams
Ex: How many grams are in .277 moles of H2O?
molar mass=
18.0 grams
Ex: How many moles are in the Statue of Liberty if 81,300 kg of copper were used?
molar mass=
63.6 grams
Ex: How many molecules are in 50 g of Mg3(PO4)2?
molar mass=
262.9 grams
How can I use factor-label to explain the mole?
T. O’Toole
Minute Paper
How do I get from where I am to where I’m going?
The 10 Minute Makeover
Customize your learning by choosing from the following options each night
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Complete the appropriate section on the Portfolio Page
Watch the 4 videos showing factor label with Molar Mass
and also Avogadro’s Number found in the Video Resources
tab of the Livebinder
Complete SYS Assignment related book work
Review the PPT file on the website
Read pages 176-186 in the book
Answer question #27 on page 186. The answer is in Appendix C.
Practice calculating molar mass using: http://www.quia.com/cm/147186.html
Practice molar mass factor label using: http://www.quia.com/cb/233133.html
Practice MOLE factor label using: http://www.quia.com/cb/234662.html
Practice with the mole using: http://www.quia.com/rr/265659.html
Check out the tutorial resources in the LiveBinder
Review the skills from today’s Train Your Brain
How can I use factor-label to explain the mole?
T. O’Toole