The MOLE! No, not the animal…Yes, this is chemistry

Know your targets!

• Students should be able to…– Determine the molar mass of an element or

compound– Use the factor-label method to convert between: • Moles• Mass• Number of atoms or molecules• Volume of a gas

A What?!?

A mole is a unit!

A “mole” is a unit

• How many is a dozen? 12• How many is a baker’s dozen? 13• How many is a couple? 2• How many is a few? 3 or 4• How many is a decade? 10• How many is a mole?...the number of

particles (TBA) within a mole is always the same regardless of the type of substance

When do we use moles?

• The Fed-Ex Story – Moral?

• The Chuck E Cheese Story– Moral?

Molar Mass

• Molar mass is the mass of one mole of any element or compound.

• The molar mass for elements is found by looking at the atomic masses on the Periodic Table.

• The units for molar mass are “grams per mole”

Compare Aluminum and Gold

Aluminum (Al) Gold (Au)

Molar Mass= 27.0 g/mol Molar Mass= 197.0

Molar Mass for Compounds

• Molar Masses are equal to the sums of the molar masses of all atoms in one molecule of that chemical compound

Ex. NaCl Contains one atom of sodium and one atom of chlorine.

(1 atom x 23.0 g/mole Na) + (1 atom x 35.5 g/mole Cl) = 58.5 g/mole NaCl

Molar Mass for Compounds

• A chemical formula with a subscript: Multiply the atoms of anything next to the subscript by the number of the subscript

Ex. FeCl2

contains one atom of iron and 2 of chlorine

(1 atom x 56 g/mole Fe) + (2 atoms x 35.5 g/mole of Cl) = 127 g/mole of FeCl2

Molar Mass for Compounds

• Other compounds: Ex. Zn(NO3)2

Zn + NO3 + NO3

Zn + N + O + O + O + N + O + O + OContains one zinc atom, two nitrogen atoms, and six oxygen

atoms

(1 atom x 65 g/mole of Zn) + (2 atoms x 14 g/mole of N) + (6 atoms x 16 g/mole of O) = 189 grams/mole of zinc nitrate

NN OONNOO

OOOO

OO OO

Molar Mass: Your Turn

1. Li2. KOH 3. BF3

4. Mg(OH)2

5. H3PO4

6. (NH4)2SO4

Molar Mass: Answers

1. 6.9 g/mol2. 56.1 g/mol3. 67.8 g/mol4. 58.3 g/mol5. 98.0 g/mol6. 132.1 g/mol