The Mole and Molar Mass

1

The Moleand

Molar Mass

What’s missing?

The measurements!

A warm up…1 trio = 3 singers

1 six-pack Cola = 6 cans soda

1 dozen donuts = 12 donuts

1 gross of pencils = 144 pencils

Moles of ParticlesContains 6.02 x 1023 particles

1 mole (mol) C = 6.02 x 1023 C atoms 1 mol H2O = 6.02 x 1023 H2O molecules

1 mol NaCl = 6.02 x 1023 Na+ ions and 6.02 x 1023 Cl– ions

Examples of MolesMoles of elements

1 mol Mg = 6.02 x 1023 Mg atoms 1 mol Au = 6.02 x 1023 Au atoms

Moles of compounds1 mol NH3 = 6.02 x 1023 NH3 molecules1 mol C9H8O4 = 6.02 x 1023 aspirin

molecules

Avogadro’s Number6.02 x 1023 particles

1 mole

or

1 mole6.02 x 1023 particles

Molar MassNumber of grams in 1 mole =

the atomic mass

1 mole of C atoms = 12.0 g1 mole of Mg atoms = 24.3 g1 mole of Cu atoms = 63.5 g

What are the number of atoms in 0.500 mol of Al?3.01 x 1023 Al atoms

0.500 mol Al 6.02 x 1023 Al atoms 1 mol Al

What are the number of moles of S if a sample of S contains 4.50 x 1024 S atoms?

7.5 mol S atoms

4.50 x 1024 S atoms 1 mol S 6.02 x 1023 S atoms

Learning Check

Learning CheckCalculate the molar mass

A. 1 mole of Br atoms =________

B. 1 mole of Sn atoms = ________

79.9 g/mole

118.7 g/mole

Molar Mass of Compounds

Mass of compounds in g/mol = the sum of all of its atomic masses

CaCl2 (1 mole Ca x 40.1 g/mol) + (2 moles Cl x 35.5 g/mol)

1 mole of CaCl2 = 111.1 g/mol

N2O4 (2 moles N x 14.0 g/mole) + (4 moles O x 16.0 g/mole)

1 mole of N2O4 = 92.0 g/mole

Molar Mass of Compounds

Calculations with Molar Mass

Grams Moles Atoms/Molecules

Use 6.02 x 1023 (particles/mole)Use molar mass

(grams/mole)

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Moles and GramsAluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al?

1. Molar mass of Al = 27.0 g Al2. Conversion factors for Al

27.0g Al or 1 mol Al 1 mol Al 27.0 g Al3. Setup 3.00 mol Al 27.0 g Al

1 mol AlAnswer = 81.0 g Al

Learning Check The artificial sweetener

aspartame (Nutri-Sweet) formula C14H18N2O5 is used to sweeten diet foods, coffee and soft drinks. How

many moles of aspartame are present in 225 g of aspartame?

Solution1. Molar mass of Aspartame C14H18N2O5

(14 x 12.0) + (18 x 1.01) + (2 x 14.0) + (5 x 16.0) = 294 g/mole

2. Setup 225 g aspartame 1 mole aspartame 294 g aspartame

Answer = 0.765 moles of aspartame

Learning Check How many atoms of Aluminum

are in 17 grams of Aluminum?

17 grams Al 1 mole Al 6.02 x 1023 atoms 27.0 grams Al 1 mole Al

Answer = 3.8 x 1023 atoms of Al