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Molar Mass, Moles, and Avogadro's Number

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Molar Mass, Moles, and Avogadro's Number Molar Mass, Moles, and Avogadro’s Number • Bell schedule: Period 1 - 8:00 - 9:07 (67 mins) Passing - 9:07 - 9:12 (5 mins) Period 2 S/L Activity - 9:12 - 9:59 (47 Mins) Recess - 9:59 - 10:09 (10 mins) Passing - 10:09 - 10:14 (5 mins) Period 2 - 10:14 - 11:21 - (67 mins) Lunch - 11:21 - 11:51 (30 mins) Passing - 11:51 - 11:56 (5 mins) Period 3 - 11:56 - 1:03 (67 mins) Passing - 1:03 - 1:08 (5 mins) Period 4 - 1:08 - 2:15 (67 mins) PSAT – Oct. 25th • 10th and 11th grade Warm Up 10-16 1) Balance the following chemical equation: Li2O + H2O LiOH 2) How many reactants does the equation have? 3) In your balanced equation, how many molecules of the product do you end up with? Molar Mass, Moles, and Avogadro’s Number Molar Mass Molar mass is the mass of one molecule You calculate it by adding the atomic mass of each atom in the molecule together The units for molar mass are g/mol (grams per mole) Molar Mass Let’s look at CO2 C 12 * 1 = 12g/mol O2 16 * 2 = 32g/mol Molar Mass of CO2 = 12 + 32 = 44g/mol Practice Find the molar mass of H2O H2 1 * 2 = 2g/mol O 16 * 1 = 16g/mol Molar Mass of H2O = 2 + 16 = 18g/mol Molar Mass You only every find molar mass for a single molecule, so ignore the coefficients! Example: What is the molar mass of H2O in the chemical equation below? 6H2SO3 6H2O + 6SO2 The molar mass of H2O is still 18g/mol even though you have a coefficient of 6 Practice 2Ca(OH)2 + 2CO2 2CaCO3 + 2H2O Find the molar mass of Ca(OH)2 Ca: 40 x 1 = 40g/mol O: 16 x 2 = 32g/mol H: 1 x 2 = 2g/mol Molar Mass of Ca(OH)2 = 40 + 32 + 2 = 74g/mol What is a mole? A mole (mol) is a standard unit that measures the mass of one molecule The mass of a mol will be different based on the molecule. Que es un mole? We just found that 1 molecule of H2O had a molar mass of 18g/mol This means that 1 mol of H2O has a mass of 18g We also found that 1 molecule of CO2 had a molar mass of 44g/mol This means that 1 mol of CO2 has a mass of 44g What is a mole? So we know 1 mol of H2O has a mass of 18g …doesn’t that seem like a lot for a molecule? 18 grams is about the mass of 3 quarters!! What is a mole? 1 mole is actually 6.022 x 1023 particles This means that if we took 602,200,000,000,000,000,000,000 molecules of H2O, they would have a mass of 18 grams together. This is known as Avogadro’s Number: 6.022 x 1023 1 mole of any molecule has this many particles! Amedeo Avogadro There is 1 mole of water in 18mL…. So there are 602,200,000,000,000,000,000,000 molecules of H2O in 3.65 teaspoons Practice How many CO2 molecules are in 1 mole of Carbon Dioxide? 6.022 x 1023 Practice How many Silver atoms are in 1 mole of Silver? 6.022 x 1023 Practice How many (NH4)2CO3 atoms are in 1 mole of Ammonium Carbonate? 6.022 x 1023.
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