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CHEMICAL QUANTITIES All Roads Lead to the Mole

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Chemical Quantities Measuring donuts: 1 dozen = 12 donuts (count) 1 dozen = 500 g donuts (mass) 1 dozen = 1 box donuts (volume) Measuring steam (H 2 O gas): 1 mole = 6.02 x H 2 O molecules (count) 1 mole = 18.0 g H 2 O (mass) 1 mole = 22.4 L H 2 O (volume) at STP Dozen: Baker as Mole: Chemist

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Count Amedeo Avogadro 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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AVOGADRO’S CONSTANT = 6.02 x Not to be confused with the delicious fruit

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AVOGADRO’S CONSTANT = 6.02 x mole = 6.02 x 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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Believe it or not, students all over the country celebrate National Mole Day! National Mole Day Foundation, INC. Mole Day

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5 Pound Bag of Sugar contains 6.6 moles Of C 12 H 22 O 11 1 Liter bottle of Water contains 55.5 moles H x Grains of Sand: Would be more than all of the sand on Miami Beach x Blood Cells: Would be more than the total number of blood cells found in every human on earth x Watermelon Seeds: Would be found inside a melon slightly larger than the moon x Pennies: Would make at least 7 stacks that would reach the moon x Donut Holes: Would cover the earth and be 5 miles (8 km) deep.

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MassVolume R.P. Molecules Atoms Formula Units Ions Draw on NOTETAKERS (and pass out flow Mole Map)

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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 MOLECULE 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 + : Cl 2 : C 2 H 6 : Cu(NO 3 ) 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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Mole R.P. Calculations 1 mole = Avogadro’s Number = 6.02 x R.P.’s R.P.

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R.P. Example 1: How many moles are in 1.4 x molecules of H 2 O?

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

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R.P. Example 3: How many atoms are in 5.2 mol CO 2 ?

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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 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: H 2 = 2H = 2(1.01) = 2.02 g/mol Problem: Find the gram formula mass for H 2 SO 4. Solution: H 2 SO 4 = 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: Find the MW of CH 4. = 1C + 4H = (1.01) = g CH 4 /mol CH 4

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MW Example 2: 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 MgSO 4 ∙7H 2 O. =Mg + S + 4O + 7(H 2 O) = (16.00) + 7( ) = g MgSO 4 ∙7H 2 O /mol MgSO 4 ∙7H 2 O

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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

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

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

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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

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Volume Example 1: Determine the volume, in liters, of mol of SO 2 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 = N 2 = 2(14.01) = g/mol Fluorine = F 2 = 2(19.00) = g/mol Nitrogen dioxide = NO 2 = (16.00) = g/mol Carbon dioxide = CO 2 = (16.00) = g/mol Ammonia = NH 3 = (1.01) = g/mol

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Mixed Mole Conversions 1 mole = 6.02 x RP’s = MW = 22.4 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?

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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)? a)23.0 g b)35.5 g c)58.44 g d)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? a)15.8 g b)58.5 g c)220 g d)6.02 x g

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What is the mass of one mole of water (H 2 O)? a)3.0 g b)16.0 g c)17.0 g d)18.02 g atomic mass H = 1.01 g/mol atomic mass O = g/mol mass of one mole of H 2 O = 2(1.01) = g

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How many moles are in 152 g of water? a)0.118 mol b)8.44 mol c)2736 mol d)6.02 x mol

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