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CHEMICAL QUANTITIES. All Roads Lead to the Mole. Measuring doughnuts: 1 dozen = 12 doughnuts (count) 1 dozen = 500 g doughnuts (mass) 1 dozen = 1 box doughnuts (volume). Measuring steam (H 2 O gas): 1 mole = 6.02 x 10 23 H 2 O molecules (count) 1 mole = 18.0 g H 2 O (mass)
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CHEMICAL QUANTITIES All Roads Lead to the Mole
Measuring doughnuts: 1 dozen = 12 doughnuts (count) 1 dozen = 500 g doughnuts (mass) 1 dozen = 1 box doughnuts (volume) Measuring steam (H2O gas): 1 mole = 6.02 x 1023 H2Omolecules (count) 1 mole = 18.0 g H2O(mass) 1 mole = 22.4 L H2O (volume) at STP Chemical Quantities Dozen: Baker as Mole: Chemist
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.
AVOGADRO’S CONSTANT= 6.02 x 1023 Not to be confused with the delicious fruit
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 The MOLE is to chemists as the DOZEN is to bakers.
Believe it or not, students all over the country celebrate National Mole Day! National Mole Day Foundation, INC. Mole Day
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.
CARRY YOUR UNITS... Volume Mass MOLE R.P. Formula Units Ions Molecules Atoms ...AND YOUR UNITS WILL CARRY YOU!
Types of Representative Particles • Molecules (breaks down into atoms) • Atoms • Formula Units (breaks down into ions) • Ions
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.
Mole R.P. Calculations 1 mole = Avogadro’s Number = 6.02 x 1023 R.P.’s R.P. MOLE
R.P. Example 1:How many moles are in 1.4 x 1022 molecules of H2O?
R.P. Example 2:How many representative particles are in 2.6 mol CO2?
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.
MW Example 1: • Find the MW of CH4. = 1C + 4H = 12.0 + 4(1.0) = 16.0 g/mol
MW Example 2: • Find the MW of Mg(OH)2. =Mg + 2O + 2H =24.3 + 2(16.0) + 2(1.0) =58.3 g/mol
MW Example 3: • Find the MW of MgSO4•7H2O. =Mg + S + 4O + 7(H2O) =24.3 + 32.1 + 4(16.0) + 7(18.0) =246.4 g/mol
What is the mass of one mole of table salt (NaCl)? • 23.0 g • 35.5 g • 58.5 g • 100.0 g Atomic mass Na = 23.0 g/mol Atomic mass Cl = 35.5 g/mol Mass of one mole of NaCl = 23.0 + 35.5 = 58.5 g
Mole Mass Calculations 1 mole = molar mass (MW) in grams Mass MOLE
Mass Example 1: Mass Example 1: How many grams are in 7.20 moles of dinitrogen trioxide? Dinitrogen trioxide = N2O3 MW of N2O3 = 2N + 3O = 2(14.0) + 3(16.0) = 76.0 g/mol 1 mole = 76.0 g N2O3
Mass Example 2: Mass Example 2: Find the number of moles in 92.2 g of iron(III) oxide, Fe2O3. Iron (III) oxide = Fe2O3 MW of Fe2O3 = 2Fe + 3O = 2(55.8) + 3(16.0) = 159.6 g/mol 1 mole = 159.6 g Fe2O3
What is the mass of 3.7 moles of NaCl? • 15.8 g • 58.5 g • 216.5 g • 6.02 x 1023 g
What is the mass of one mole of water (H2O)? • 3.0 g • 16.0 g • 17.0 g • 18.0 g Atomic mass H = 1.0 g/mol Atomic mass O = 16.0 g/mol Mass of one mole of H2O = 2(1.0) + 16.0 = 18.0 g
How many moles are in 152 g of water? • 0.118 mol • 8.44 mol • 2736 mol • 6.02 x 1023 mol
Mole Volume Calculations 1 mole = 22.4 L of gas at STP STP = standard temperature and pressure(0 °C & 1 atm) Volume MOLE
Volume Example 1: Volume Example 1: Determine the volume, in liters, of 0.600 mol of SO2 gas at STP.
Volume Example 2: Volume Example 2:Determine the number of moles in 33.6 L of He gas at STP.
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.
Density Example (part A): The density of an unknown gas at STP is 2.054 g/L. (a) What is the molar mass?
Density Example (part B): The density of an unknown gas is 2.054 g/L. (b) Identify the gas as either nitrogen, fluorine, nitrogen dioxide, carbon dioxide, or ammonia. MW = 46.0 g/mol (from part a) Nitrogen = N2 = 2(14.0) = 28.0 g/mol Fluorine = F2 = 2(19.0) = 38.0 g/mol Nitrogen dioxide = NO2 = 14.0 + 2(16.0) = 46.0 g/mol Carbon dioxide = CO2 = 12.0 + 2(16.0) = 44.0 g/mol Ammonia = NH3 = 14.0 + 3(1.0) = 17.0 g/mol
Mixed Mole Conversions 1 mole = 6.02 x 1023 RP’s = MW = 22.4 L of gas @STP All Roads Lead to the Mole. Always convert to units of moles first when converting between grams, liters, and representative particles.
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.
Mixed Mole Example 2: How many atoms are in 22.0 g of water?