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IIIIIIIV The Mole I. Molar Conversions

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A. What is the Mole? n A counting number (like a dozen) n Avogadro’s number n 1 mol = 6.02 10 23 items A large amount!!!!

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n 1 mole of hockey pucks would equal the mass of the moon! A. What is the Mole? n 1 mole of pennies would cover the Earth 1/4 mile deep! n 1 mole of basketballs would fill a bag the size of the earth!

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B. Molar Mass n Mass of 1 mole of an element or compound. n Atomic mass tells the... atomic mass units per atom (amu) grams per mole (g/mol) n Round to 2 decimal places

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B. Molar Mass Examples n carbon n aluminum n zinc 12.01 g/mol 26.98 g/mol 65.39 g/mol

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B. Molar Mass Examples n water n sodium chloride H2OH2O 2(1.01) + 16.00 = 18.02 g/mol NaCl 22.99 + 35.45 = 58.44 g/mol

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B. Molar Mass Examples n sodium bicarbonate n sucrose NaHCO 3 22.99 + 1.01 + 12.01 + 3(16.00) = 84.01 g/mol C 12 H 22 O 11 12(12.01) + 22(1.01) + 11(16.00) = 342.34 g/mol

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C. Molar Conversions molar mass (g/mol) MASS IN GRAMS MOLES NUMBER OF PARTICLES 6.02 10 23 (particles/mol)

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C. Molar Conversion Examples n How many moles of carbon are in 26 g of carbon? 26 g C 1 mol C 12.01 g C = 2.2 mol C

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C. Molar Conversion Examples n How many molecules are in 2.50 moles of C 12 H 22 O 11 ? 2.50 mol 6.02 10 23 molecules 1 mol = 1.51 10 24 molecules C 12 H 22 O 11

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C. Molar Conversion Examples n Find the mass of 2.1 10 24 molecules of NaHCO 3. 2.1 10 24 molecules 1 mol 6.02 10 23 molecules = 290 g NaHCO 3 84.01 g 1 mol

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C. Molar Conversion Examples n Find the mass of one Fe atom 1 mole Fe = 55.85g 1 mole Fe = 6.02 x 10 23 atoms 55.85 g 1 mole 6.02 x 10 23 atoms = 9.28 x 10 -23 g/atom 1 mole

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C. Molar Conversions n How many Oxygen atoms are there in 50.25 g of CaCO 3 ? 50.25g CaCO 3 1 mol CaCO 3 100.09 g 3 mol O 1 mol CaCO 3 6.02 x 10 23 atoms O 1 mol O = 9.07 x 10 23 atoms

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IIIIIIIV …and if Avogadro rings, ask him to leave his number…

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IIIIIIIV The Mole-Volume Relationship

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The Volume of a Gas n Many of the chemicals we deal with are gases They are difficult to weigh (or mass) n We need to know how many moles of gas we have n Two things effect the volume of a gas Temperature and pressure n We need to compare gases at the same temperature and pressure

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Standard Temperature and Pressure (STP) n 0°C and 1 atmosphere (atm) of pressure n At STP, 1 mole of any gas occupies 22.4 L, Called the molar volume n 1 mole = 22.4 L of any gas at STP

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Practice examples n What is the volume of 4.59 mole of CO 2 gas at STP? n How many moles is 5.67 L of O 2 at STP? n What is the volume of 8.8 g of CH 4 gas at STP?

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Molarity –Molar Volume of… Solutions! n Molarity = moles of solute/liter of solution n Note: it’s liters of solution, not liters of solvent

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Molarity Examples n Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate in 125 ml of solution n 23.4 g Na 2 SO 4 0.165 mol n 125 ml 0.125 L n M = mol / L n M = 0.165mol / 0.125 L n M = 1.32 M

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Molarity Examples n Calculate the molarity of a solution made by dissolving 5.00 g of C 6 H 12 O 6 in enough water to make 100.0 ml of solution n 0.280 M

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Molarity Examples n How many grams of Na 2 SO 4 are required to make 0.350 L of a 0.500 M solution of Na 2 SO 4 ? n 24.9 g Na 2 SO 4

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