Chapter 8 Factor Label Method and the Mole. What is Avogadro’s Favorite Novel?

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Chapter 8 Factor Label Method and the Mole

Molby Dick

A ratio is an equality is a conversion factor. Density of Aluminum = 2.7 g/cm 3 Land speed record = 763 miles/hr 1.61 km = 1 mile 1 pound = 0.4536 kilograms

What Do We Know About the Mole

1 mol = 6.02 x 10 23

What Do We Know About the Mole 1 mol = 6.02 x 10 23 Any equality or ratio can be made into a conversion factor and then used to solve problems with the factor label method.

6.02 x 10 23 “particles” 1 mole or 1 mole 6.02 x 10 23 “particles” Note that particles could be atoms, molecules, formula units, ions, etc. Avogadro’s Number as a Conversion Factor

= 6.02 x 10 23 C atoms = 6.02 x 10 23 H 2 O molecules = 6.02 x 10 23 NaCl “molecules” (technically, ionic compounds are not molecules, they are called formula units) A Mole of Particles A Mole of Particles Contains 6.02 x 10 23 particles 1 mole C 1 mole H 2 O 1 mole NaCl

What Do We Know About the Mole

1 mol of any substance = it’s gfm

What’s in a Name? Atomic Mass/Atomic Weight/Molecular Mass/Molecular Weight/Formula Mass/Formula Weight: If you have a single atom or molecule or compound, mass is measured in amu’s. Gram Atomic Mass/Gram Atomic Weight/Gram Molecular Mass/Gram Molecular Weight/Gram Formula Mass/Gram Formula Weight/Molar Mass: If you have a mole of atoms or molecules or a compound, mass is measured in grams. But, the numerical value is the same whether you have 1 mole or one particle. Only the units are different. (This is the beauty of Avogadro’s Number!). THE POINT: You may hear all of these terms which mean the SAME NUMBER… just different units.

Equal to the atomic mass (get from chart) The mass of 1 mole (in grams) 1 mole of C atoms= 12.0 g Gram Atomic Mass (Molar Mass) of an atom

1 mole of Mg atoms Gram Atomic Mass (Molar Mass) of an atom 24.3 g

1 mole of Cu atoms Gram Atomic Mass (Molar Mass) of an atom 63.5 g

Gram Formula Mass (Molar Mass) of Molecules and Compounds

Mass in grams of 1 mole Equal to the formula mass (sum of the atomic masses) expressed in grams Gram Formula Mass (Molar Mass) of Molecules and Compounds

Mass in grams of 1 mole Equal to the formula mass (sum of the atomic masses) expressed in grams Gram Formula Mass of Ca 3 (PO 4 ) 2 3 x 40.1 = 120.3 2 x 31.0 = 62.0 8 x 16.0 = 128.0 = 310.3 g/mol Gram Formula Mass (Molar Mass) of Molecules and Compounds

List “2” things you know about a mole of H. 1 mole H = 6.02 x 10 23 H atoms 1 mole H = 1.0g What could we use these equalities to do in a factor label problem?

List “2” things you know about a mole of H 2 O 1 mole H 2 O = 6.02 x 10 23 H 2 O molecules 1 mole H 2 O = 18.0g

List “2” things you know about a mole of Na 2 O 1 mole Na 2 O = 6.02 x 10 23 Na 2 O formula units 1 mole Na 2 O = 62.0g