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CHEMICAL QUANTITIES

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

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  1. CHEMICAL QUANTITIES All Roads Lead to the Mole

  2. 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

  3. 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.

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

  5. 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.

  6. A Mole Balance

  7. Believe it or not, students all over the country celebrate National Mole Day! National Mole Day Foundation, INC. Mole Day

  8. 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.

  9. CARRY YOUR UNITS... Volume Mass MOLE R.P. Formula Units Ions Molecules Atoms ...AND YOUR UNITS WILL CARRY YOU!

  10. Types of Representative Particles • Molecules (breaks down into atoms) • Atoms • Formula Units (breaks down into ions) • Ions

  11. Naming Representative Particles

  12. 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.

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

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

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

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

  17. 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.

  18. MW Example 1: • Find the MW of CH4. = 1C + 4H = 12.0 + 4(1.0) = 16.0 g/mol

  19. 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

  20. 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

  21. 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

  22. Mole Mass Calculations 1 mole = molar mass (MW) in grams Mass MOLE

  23. 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

  24. 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

  25. What is the mass of 3.7 moles of NaCl? • 15.8 g • 58.5 g • 216.5 g • 6.02 x 1023 g

  26. 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

  27. How many moles are in 152 g of water? • 0.118 mol • 8.44 mol • 2736 mol • 6.02 x 1023 mol

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

  29. Volume Example 1: Volume Example 1: Determine the volume, in liters, of 0.600 mol of SO2 gas at STP.

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

  31. 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.

  32. Density Example (part A): The density of an unknown gas at STP is 2.054 g/L. (a) What is the molar mass?

  33. 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

  34. 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.

  35. 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.

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

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