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What is a Mole?

Mole Video

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What is a mole?

No!! Not that kind of mole!

Unit of measure that is important in understanding the relationship between the number of particles in a substance and its’ mass.

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The Mole

No! Not that kind of mole.

A mole (mol) is the amount of a substance that contains as many particles as there are atoms in 12g of C-12.

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Avagadros Number

Avagadro’s number- determined experimentally

6.022 x 1023units = 1 mole

“Units” can be atoms, particles, formula units or molecules

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Check these out!

I have measured exactly 1.00 mol of a bunch of household items. Pass them around.

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Molar Mass

The amount of substance that contains Avogadros number of particles.

Units: grams/mol

Atomic mass (amu) = Molar mass (g/mol)

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The Periodic TableSo, when we look at

the periodic table, we have a bunch of conversion factors that will help us do all sorts of calculations.

Yipee!

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How do I do gram to particle calculations?

Flow chart:

Gram Mole Particle

Using the flow chart, we can solve any of these seemingly difficult

calculations.

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Now, let’s determine the number of moles! Fun huh?

How many moles in 20.0 g of Boron?

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Practice makes perfect!

How many moles in 68.7g of Lithium?

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Can we go the other way?

How many grams in 2.61 moles of Chlorine atoms?

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How many moles are present in 8.32 x 1025 atoms of silver?

How many atoms in 2.3 mol of silver?

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Now let’s take it all the way!

How many atoms in 3.0g of Carbon?

How many grams in 1.2 x 1023 atoms of carbon?

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Work on you WS….

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Molar MassA compound is a collection of atoms that

are chemically bonded together.

Molar mass is the mass in grams of one mole of the compound.

You may also hear this quantity referred to as molecular weight.

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What is the Molar Mass of water?

1. Count how many atoms of each element.

2. Multiply by the atomic mass rounded to the 0.01 place.

3. Add them up!

QuickTime™ and a decompressor

are needed to see this picture.

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Examples

CO2

1 Carbon atom 1(12.01)g2 Oxygen atoms 2(16.00g) = 32.00g

12.01g + 32.00g = 44.01g

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Easy Huh? Try these!

NaOH

MnO4

Cu3(PO4)2

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NaOH 1 Na 23.00g1 O 16.00g1 H 1.01g

23.00g + 16.00 g + 1.01g =40.01g

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Manganese (IV) oxide

MnO2

Mn 1(54.94) O 2(16.00)

54.94g/mol + 32.00g/mol = 86.94g/mol

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Copper (II) Phosphate

Cu3(PO4)2

Copper 3(63.55)

Phosphorus 2(30.97)Oxygen 8(16.00)

380.59 g/mol

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How many formula units in 3.45 g of NaOH?

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How many grams are in 1.06 x 1027 formula units of MnO2?

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Now, lets combine what we’ve learned to do a problem you may see on the exam.

Methane is a gas. Its molecular formula is CH4. How many moles are in 20.0g of methane?

Steps1. Determine the molar mass2. Use the answer in #1 as a conversion factor to change grams to moles.