THE MOLE CONCEPT

Objects are usually measured by counting or by weight (mass) It’s easier to measure large objects by counting –Elephants, cars, eggs It’s easier to measure small objects by weight (mass) –Grass seeds, rice grains, BB’s THE MOLE CONCEPT

A mole of any ordinary object is a staggering number of atoms or molecules, however, atoms or molecules are not ordinary objects. They are much smaller than ordinary objects. Therefore 1 mole is not such a staggering amount by mass! Most molar masses can fit into the palm of your hand. THE MOLE CONCEPT

Defining the Mole Definition of the mole (mol) –One mole is the amount of any substance that contains the same number of particles as the number of atoms in exactly 12 grams of Carbon-12 –12 grams of Carbon-12 = 1 mole Carbon-12 –1 mole = 6.02 x particles of Carbon-12 (atoms) –6.02 x is known as Avogadro’s Number –1 mole of other materials might be molecules

1 mole of Fe atoms is grams grams of Fe is 6.02 x atoms Defining the Mole

THE MOLE CONCEPT Substance Atomic Mass (grams/mole) Number of Particles (atoms) Al27.0 g/m6.02 x Fe55.8 g/m6.02 x Ca40.1 g/m6.02 x Na23.0 g/m6.02 x 10 23

Atomic mass & Molar Mass Atomic Mass - Mass of a mole of atoms of an element (6.02E23 atoms) Molar Mass – Mass of a mole of molecules of a compound (6.02E23 molecules)

1 mole of H 2 O has 6.02e23 molecules 1 mole of H 2 O has a mass of 18.0 grams 1 mole H 2 O has 2 moles of Hydrogen(2.0g) 1 mole H 2 O has 1 mole Oxygen(16.0g) 18.0 g of H 2 O contains 6.02e 23 molecules Defining the Mole

How to calculate Molar Mass 1 molecule of Sugar (C 6 H 12 O 6 ) – 6 atoms C, 12 atoms H, 6 atoms O 1 mole of Sugar (C 6 H 12 O 6 ) 6 moles C x 12.0 g/m = 72.0 g 12 moles H x 1.0 g/m = 12.0 g 6 moles O x 16.0 g/m = 96.0 g ______ grams/mole

We can measure 16.0 grams of CH 4 and 32.0 grams of O 2 These amounts are called Molar Mass and measured in grams/mole. When you measure out 1 Molar Mass of a substance, you have weighed out 6.02e23 molecules of that substance. THE MOLE CONCEPT

Substance Atomic or Molar Mass (grams) Number of Particles Al27.0 g6.02 x O2O g6.02 x CO g6.02 x C 6 H 12 O g6.02 x 10 23

CH O 2 → CO H 2 O Equations can be read on either of 2 levels –Molecular level - 1 molecule of CH 4 will combine with 2 molecules of O 2 to produce one molecule of CO 2 and 2 molecules of H 2 O. or –Mole Level - 1 mole of CH 4 reacts with 2 moles of O 2 to produce 1 mole of CO 2 and 2 moles of H 2 0. THE MOLE CONCEPT

–Masses of reactants = Masses of products –Law of Conservation of Matter CH O 2 → CO H 2 O 16 g + 2(32g)  44g + 2(18g) 16g + 64g  44g + 36g 80 g  80 g THE MOLE CONCEPT

Using chemical formulas molecular formulas give atom-to-atom, atom-to-molecule, mole-to-mole and mass –to-mole ratios example: molecular formula C 6 H 12 O 6 6 atoms C 6 atoms O 12 atoms H 6 atoms O 6 atoms C 1 molecule 12 atoms H 1 molecule 6 moles C____ 1mole C 6 H 12 O 6

Sample Mole Problem If you have.5 lb of C 6 H 12 O 6, find the following: A. moles of C 6 H 12 O 6 B. molecules of C 6 H 12 O 6 C. atoms of C D. atoms of H E. total atoms present F. grams of oxygen in the sample

.5lb C 6 H 12 O 6 454g C 6 H 12 O 6 1mol C 6 H 12 O 6 A. ___________ X _____________ X _____________ = 1.26 mol C 6 H 12 O 6 1 1lb C 6 H 12 O 6 180g C 6 H 12 O mol C 6 H 12 O e23 molecules B. ________________ X _________________ = 7.59e23 molecules 1 1 mol C 6 H 12 O e23 molecules 6 atoms C C. __________________ X ______________ = 4.55e24 atoms of C 1 1 molecule 7.59e23 molecules 12 atoms H D. __________________ X ______________ = 9.11e24 atoms of H 1 1 molecule 7.59e23 molecules 24 atoms TOTAL E. __________________ X _______________ = 1.82e25 atoms TOTAL 1 1 molecule 1.26 mol C 6 H 12 O 6 6 mol O 16 g O F. _______________ X _______________ X _______________ = 121 g O 1 1 mol C 6 H 12 O 6 1 mol O _

1 mole of any substance = 6.02 x units of that substance. If you spread 1 mole of un-popped popcorn kernels across the USA the entire country would be covered in popcorn to a depth of over 9 miles. If 1 mole of marbles were spread over the surface of the Earth, our planet would be covered by a 50-mile thick layer of marbles. 1 mole of soft drink cans would cover the surface of the earth to a depth of over 200 miles IMAGINE:

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