Section 3.1 The Mole and Molar Mass

The Mole and Molar Mass In this section… Connecting the atomic and real worlds The mole Elemental molar mass Compound molar mass Conversions between atoms, moles, and mass

How do we relate atoms and molecules to the real world? 1 “mole” of atoms or molecules fills a small handful.

1 mole = 6.02 x 1023 atoms or molecules 1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl22H2O

1 mole = 6.02 x 1023 atoms or molecules 1 mole of elements Cu, Al, S,

1 mole = 6.02 x 1023 atoms or molecules 1 mole compounds K2Cr2O7, H2O and CuCl22H2O

The mole as a conversion factor 1 mol element = 6.02 x 1023 atoms of that element

The mole as a conversion factor 1 mol element = 6.02 x 1023 atoms of that element moles atoms 1.95 mol Al atoms moles 4.68 x 1023 Cu atoms

The mole as a conversion factor 1 mol element = 6.02 x 1023 atoms of that element moles atoms When doing these calculations, does it matter which element is used? atoms moles

Elemental molar mass elemental molar mass = mass of 6.02 x 1023 atoms elemental molar mass = atomic weight on periodic table, in grams per mole

Molar mass 1 mol Al = 1 mol F =

Molar mass as a conversion factor 1 mol Al = molar mass Al = 26.98 g Al moles grams 1.95 mol Al 1.95 mol Al

Molar mass as a conversion factor 1 mol Cu = molar mass Cu = 63.55 g Cu grams moles 49.4 g Cu 49.4 g Cu

Compound molar mass compound molar mass = mass of 6.02 x 1023 molecules compound molar mass = sum of atomic weights of atoms in the molecule SO2

Converting between grams and moles for a compound Step 1. Determine molar mass Step 2. Use molar mass as a conversion factor

Molar mass as a conversion factor SO2 = 64.06 g/mol moles grams What is the mass of a 1.45 mol sample of SO2? grams moles What amount, in moles, of SO2 does a 212-g sample represent?

Multistep Problems How many oxygen atoms are present in a 212-g sample of SO2? Problem Map: