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**All Roads Lead to the Mole**

CHEMICAL QUANTITIES All Roads Lead to the Mole

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**Chemical Quantities Dozen: Baker as Mole: Chemist Measuring donuts:**

1 dozen = 12 donuts (count) 1 dozen = 500 g donuts (mass) 1 dozen = 1 box donuts (volume) Measuring steam (H2O gas): 1 mole = 6.02 x 1023 H2O molecules (count) 1 mole = 18.0 g H2O (mass) 1 mole = 22.4 L H2O (volume) at STP

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**Count Amedeo Avogadro 1776-1856**

Lawyer who became interested in math and physics Discovered that equal volumes of different gases contained an equal number of particles. 9 years after his death, Joseph Loschmidt determined a constant and named it after Avogadro.

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**Not to be confused with the delicious fruit**

AVOGADRO’S CONSTANT = 6.02 x 1023 Not to be confused with the delicious fruit

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**AVOGADRO’S CONSTANT = 6.02 x 1023**

1 mole = 6.02 x 1023 particles 1 mole = molar mass (grams) 1 mole (of a gas at STP) = 22.4 L

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The mole is to chemists as the dozen is to bakers.

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A Mole Balance

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**Believe it or not, students all over the country celebrate National Mole Day!**

National Mole Day Foundation, INC. Mole Day

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How BIG is a MOLE? 5 Pound Bag of Sugar contains 6.6 moles Of C12H22O11 1 Liter bottle of Water contains 55.5 moles H20 6.02 x 1023 Grains of Sand: Would be more than all of the sand on Miami Beach. 6.02 x 1023 Blood Cells: Would be more than the total number of blood cells found in every human on earth. 6.02 x 1023 Watermelon Seeds: Would be found inside a melon slightly larger than the moon. 6.02 x 1023 Pennies: Would make at least 7 stacks that would reach the moon. 6.02 x 1023 Donut Holes: Would cover the earth and be 5 miles (8 km) deep.

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**...AND YOUR UNITS WILL CARRY YOU!**

Draw on NOTETAKERS (and pass out flow Mole Map) CARRY YOUR UNITS... Volume Mass MOLE R.P. Formula Units Ions Molecules Atoms ...AND YOUR UNITS WILL CARRY YOU!

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**Types of Representative Particles**

Molecules (break down into atoms) Atoms Formula Units (break down into ions) Ions

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**Naming Representative Particles**

Pure Substance Element Monotomic Charged ION Neutral ATOM Polyatomic MOLECULE Compound Molecular Ionic FORMULA UNIT

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**Naming Representative Particles**

Examples: Name the representative particle for each substance given. For each molecule, state how many atoms are present. For each formula unit, state how many ions make up the ionic compound. H+: Cl2: C2H6: Cu(NO3)2: Al: NaCl: ION MOLECULE – 2 ATOMS per molecule MOLECULE – 8 ATOMS FORMULA UNIT – 3 IONS per Form.U. ATOM FORMULA UNIT – 2 IONS per Form.U.

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**WS: Representative Particles**

Do WS #1-20

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**1 mole = Avogadro’s Number = 6.02 x 1023 R.P.’s**

Mole R.P. Calculations 1 mole = Avogadro’s Number = 6.02 x 1023 R.P.’s R.P. MOLE

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**R.P. Example 1: How many moles are in 1.4 x 1022 molecules of H2O?**

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**R.P. Example 2: How many representative particles are in 2.6 mol CO2?**

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**R.P. Example 3: How many atoms are in 5.2 mol CO2?**

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DO WS: The Mole and Avogadro’s Number

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MOLAR MASS The molar mass is the mass, in grams, of one mole (6.02 1023 particles) of an element (ion), a covalent molecule or a formula unit. molar mass (MM) gram atomic mass (gam) molecular weight (MW) gram molecular mass (gmm) formula mass (FM) gram formula mass (gfm) formual weight (FW)

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MASS of one MOLE Gram atomic mass (gam): the atomic mass (the mass in one mole of a substance) of an element expressed in grams. Gram molecular mass (gmm): the atomic mass of one mole of a molecular compound. Gram formula mass (gfm): the sum of the atomic masses of the atoms that are in the formula of a compound.

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gam, gfm, gmm examples: Problem: Give the gram atomic mass of hydrogen. Solution: H = 1H = 1(1.01) = 1.01 g/mol Problem: Give the gram molecular mass of hydrogen. Solution: H2 = 2H = 2(1.01) = 2.02 g/mol Problem: Find the gram formula mass for H2SO4. Solution: H2SO4 = 2H + 1S + 4O = 2(1.01) (16.00) = g/mol

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**Molar Mass … a.k.a. Molecular Weight (MW)**

molar mass = mass of 1 mole of substance Molar mass can be determined by adding up the atomic masses from the periodic table (atomic mass goes to 2 decimal places).

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**MW Example 1: = 1C + 4H = 12.01 + 4(1.01) = 16.05 g CH4/mol CH4**

Find the MW of CH4. = 1C + 4H = (1.01) = g CH4/mol CH4

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**MW Example 2: =Mg + 2O + 2H =24.31 + 2(16.00) + 2(1.01)**

Find the MW of Mg(OH)2. =Mg + 2O + 2H = (16.00) + 2(1.01) =58.33 g Mg(OH)2 /mol Mg(OH)2

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**MW Example 3: Find the MW of MgSO4∙7H2O. =Mg + S + 4O + 7(H2O)**

= (16.00) + 7( ) = g MgSO4∙7H2O /mol MgSO4∙7H2O

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Calculations: Use Mole Map to help calculate

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**Mole Mass Calculations**

1 mole = molar mass (MW) in grams Mass MOLE

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Mass Example 1: How many grams are in 7.20 moles of dinitrogen trioxide? dinitrogen trioxide = N2O3 MW of N2O3 = 2N + 3O = 2(14.01) + 3(16.00) = g/mol 1 mole = g N2O3

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**MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = 159.70 g/mol**

Mass Example 2: Find the number of moles in 92.2 g of iron(III) oxide. iron(III) oxide = Fe2O3 MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = g/mol 1 mole = g Fe2O3

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**Make sure you write out all work and include all units!!**

Practice Worksheet Do #1-10 on Mole and Mass WS Make sure you write out all work and include all units!!

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**Mole Volume Calculations**

1 mole = 22.4 L of gas at STP STP = standard temperature and pressure (0 °C & 1 atm) Volume MOLE

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Volume Example 1: Determine the volume, in liters, of mol of SO2 gas at STP.

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Volume Example 2: Determine the number of moles in 33.6 L of He gas at STP.

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**Density density = mass / Volume**

When given the density of an unknown gas, one can multiply by the molar volume to find the MW. The MW can allow for identification of the gas from a list of possibilities.

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**Density Example (part A):**

The density of an unknown gas is g/L at STP. (a) What is the molar mass?

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**Density Example (part B):**

The density of an unknown gas is g/L (b) Identify the gas as either nitrogen, fluorine, nitrogen dioxide, carbon dioxide, or ammonia. MW = g/mol (from part a) Nitrogen = N2 = 2(14.01) = g/mol Fluorine = F2 = 2(19.00) = g/mol Nitrogen dioxide = NO2 = (16.00) = g/mol Carbon dioxide = CO2 = (16.00) = g/mol Ammonia = NH3 = (1.01) = g/mol

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**Mixed Mole Conversions**

1 mole = x 1023 RP’s = MW = L of All Roads Lead to the Mole. Always convert to units of moles first when converting between grams, liters, and representative particles.

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**Mixed Mole Example 2: How many atoms are in 22.0 g of water?**

22.0 g H2O × 1 mole H2O g H2O × 6.02×1023 molec. H2O 1 mole H2O × 3 atoms 1 molec. H2O

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Mixed Mole Example 1: How many carbon atoms are in a 50.0-carat diamond that is pure carbon? Fifty carats is the same as 10.0 g.

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**Extra questions to review concepts**

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**What is the mass of one mole of table salt (NaCl)?**

23.0 g 35.5 g 58.44 g 100.0 g atomic mass Na = g/mol atomic mass Cl = g/mol mass of one mole of NaCl = = g

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**What is the mass of 3.7 moles of NaCl?**

15.8 g 58.5 g 220 g 6.02 x 1023 g

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**What is the mass of one mole of water (H2O)?**

3.0 g 16.0 g 17.0 g 18.02 g atomic mass H = 1.01 g/mol atomic mass O = g/mol mass of one mole of H2O = 2(1.01) = g

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**How many moles are in 152 g of water?**

6.02 x 1023 mol

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