MOLAR MASS

What is molar mass?How do you calculate molar mass?

WHAT IS MOLAR MASS?

• mass in grams of 1 mole of the element

• Molar Mass = ___grams____(MM) 1

Mol

Synonyms: molecular weight, gram formula unit

Use Periodic Table to determine MM!

• Let’s examine periodic table! • If I had one mole of _____ it’s molar mass would

be _______ g per 1 mol.

• Carbon MM= 12.0 g / mol

• Atomic Hydrogen MM= 1.0 g / mol

• Mercury MM= 200.6 g / mol

• Iron MM=55.8 g / mol

• Sulfur MM= 32.1 g / mol

How many particles do these elements contain?

Particles: 1. Atoms2. Formula Units3. Molecules

How do you calculate molar mass of compounds?

• EX. Sulfur Trioxide Chemical Formula = _____________

• How many total atoms make up one molecule? • Atoms = _____________ • S: ___ x ______ = • O: ___ x ______ = _____ +

• The molar mass of sulfur trioxide = _______ grams per

________

SO3

1 + 3 = 41

3

32.1 32.1

16.0 48.0

80.1

80.11 mol

Your Turn• EX. Phosphorus Trichloride Chemical Formula =

__________• How many total atoms make up one molecule? Atoms = ________

• P: ___ x ______ = • Cl: ___ x ______ = _________ +

• Sodium Hydrogen Carbonate NaHCO3

PCl3

1+3=4

1 31.0 31.0

3 35.5 106.5137.5 grams per 1 mol

MM = 84.0 g / mol

Representative Particles• Covalent Compounds are made up of _____.• Ionic Compounds are made up of _________. • Elements are made up of _____________.

• Use your Road Map!

molecules

Formula units

atoms

Conversions Using Molar Mass• Book pg. 298 • Ex. #1 Write the chemical formula for aluminum oxide _________• What is given?

Trying to find?

• ______________ x _______________ = g of Al2O3

GIVEN

Al2O3

9.45 moles Al2O3

g of Al2O3

Al: 2 x 27.0 = 54.0 gO: 3 x 16.0 = 48.0 g +

102.0 g / 1 mol

9.45 moles

1 Mole Al2O3

102.9 grams Al2O3 964

Molar Volume Conversions

• At STP (Standard Temp and Pressure):

• 1 mole of gas = 22.4 L = 6.02 x 1023 particles

1 Mole of ANY GAS at STP!

• Sample Problem 10.7 Use our Mole Road Map! • Sample Problem 10.8

• REMEMBER! Density = mass = grams

Volume Liter• HINT: If given density, first find the molar mass

(MM) = grams per mol