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Lesson Objectives Define the mole (8A) Use the concept of the mole (8A)

Lesson Objectives Define the mole (8A) Use the concept of the mole (8A) Using the mole, calculate the number of particles in a sample (8B) mol ⬄ gram particles ⬄ mol particles ⬄ gram. The Mole. Mole – unit of measurement that is equal to 6.02 × 10 23 particles

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Lesson Objectives Define the mole (8A) Use the concept of the mole (8A)

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  1. Lesson Objectives • Define the mole (8A) • Use the concept of the mole (8A) • Using the mole, calculate the number of particles in a sample (8B) • mol⬄gram • particles⬄mol • particles⬄gram • The Mole

  2. Mole – unit of measurement that is equal to 6.02 × 1023 particles • Particle – a very small piece of matter • Examples of different types of particles include atoms, ions, electrons, molecules and formula units • Avogadro’s number = 6.02 × 1023 particles • Avogadro’s number is based on the number of atoms in 12 g of carbon-12 • Mole is abbreviated as mol • The Mole

  3. A mole is a unit based on number of particles not mass • Each element has a unique mass • Substances with the same number of moles can have different masses • Mass and Moles

  4. Molar Mass • Molar mass– mass of one mole of pure substance • Units of g/mol atomic mass Ex) Molar mass of Sr • Molar mass of a single element is numerically equal to its atomic mass 87.62 g/mol

  5. Subscripts indicate the number of atoms of each element in the formula • Absence of a subscript indicates there’s only one atom • Subscript Review Ex) H2O2 2 H 2 O H Ex) NH3 O O 1 N H 3 H N H H H

  6. Parentheses Review • Subscripts placed outside parentheses apply to all the elements inside the parentheses Ex) Mg(OH)2 1 Mg • Multiply any subscripts inside the parentheses by the subscript outside to find the total number of atoms of each element [ ]– 2+ [ ]– 2 O 2 H

  7. Formula Mass and Molar Mass • Formula mass– total of the atomic masses of the atoms in a formula • Molar mass of a compound is numerically equal to the formula mass Ex) Formula mass of MgBr2 24.305 1 atom Mg × 24.305 = 159.808 2 atoms Br × 79.904 = + 184.113

  8. Molar Masses of Compounds • Considering the number of moles of each element present, the molar mass of a compound equals the sum of the molar masses of its elements • Subscripts in the formula indicate the number of moles of atoms of each element in one mole of the compound Ex) Molar mass of MgBr2 1 mol Mg × 24.305 g/molMg = 24.305 g Mg 2 mol Br × 79.904 g/molBr = 159.808 g Br + 184.113 g/mol MgBr2

  9. Calculating Molar Masses • Multiply the molar mass of each element by the number of moles of that element in the compound • Add the masses of all the elements together Ex) Molar mass of Mg(OH)2 1 Mg × 1 = 24.305 = 24.305 2 O = 15.999 × 2 = 31.998 2 H = 1.0079 × 2 = 2.0158 + 58.319 g/mol Mg(OH)2

  10. Conversion Review • Write the given number and units • Cancel out units using conversion factors until you arrive at the units for your answer • Solve Ex) A recipe calls for 2 ½ tablespoons of peanut butter but all you have to measure with is a teaspoon. How many teaspoons are equal to 2 ½ tablespoons? 1 tbsp. = 3 tsp. Back

  11. 1 mole = 6.02 x 1023 atoms, particles, molecules, etc 1 mole = mass in grams 1 mole = 22.4 liters • Mole Conversions

  12. Mole Gram Molar Mass • To convert between grams and moles, use molar mass as a conversion factor • Mole⬄Gram Conversions Ex) mol⬄gram— How many grams are in 3.01 molFe? Ex) gram⬄mol— How many moles are in 168 g Fe?

  13. Given 5.2 grams of NaOH, how many moles are there?

  14. How many grams are in 0.62 moles of Al2(SO4)3?

  15. Particle⬄Mole Conversions • To convert between particles and moles, use Avogadro’s number (6.02 × 1023) Ex) particle⬄mol— How many moles equal 2.41 × 1024 atoms Al? Particle Mole Avogadro’s # Ex) mol⬄particle— How many atoms are in 3.45 molAl?

  16. With 1.6 moles of Cl2 howmany molecules are there?

  17. If you have 5.2x1027atoms of sodium, how many moles do you have?

  18. Particle Mole Avogadro’s # Molar Mass Gram • Particle⬄Gram Conversions • To convert between particles and grams, use both molar mass and Avogadro’s number Ex) particles⬄grams — How many grams are in 7.00 × 1033molecules H2O? Ex) grams⬄particles — How many molecules are in 8.25 g H2?

  19. The Long Road Mr. Bane has a platinum wedding band that has a mass of 6.63 grams. How many atoms are around his finger?

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