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THE MOLE

THE MOLE. ... a unit of counting. Review. How many oxygen atoms in the following? CaCO 3 Al 2 (SO 4 ) 3 How many ions in the following? CaCl 2 NaOH Al 2 (SO 4 ) 3. 3 atoms of oxygen x 6.022 x 10 23. 12 atoms of oxygen x 6.022 x 10 23. 3 total ions x 6.022 x 10 23.

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THE MOLE

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  1. THE MOLE ... a unit of counting

  2. Review • How many oxygen atoms in the following? CaCO3 Al2(SO4)3 • How many ions in the following? CaCl2 NaOH Al2(SO4)3 3 atoms of oxygen x 6.022 x 10 23 12 atoms of oxygen x 6.022 x 10 23 3 total ions x 6.022 x 10 23 2 total ions x 6.022 x 10 23 5 total ions x 6.022 x 10 23

  3. N = nNA Finding Number of Atoms or Molecules How many atoms of copper are there in 2.0 moles? N = nNA = 2.0 mol X 6.02 X 1023 atoms 1 mol = 1.2 X1024 atoms of copper Given: n Cu = 2.0 mol NA = 6.02 X 1023

  4. How we measure moles… • Do you know how to measure out 3 moles of sugar or salt or water? • The mole is a counting unit, so we would have to count out 6.02x1023 particles of each substance. (no thank you) • There are 2 ways we can use to measure out a number of moles of a substance. • Measure it in grams(amass) • Or measure it in liters(avolume)

  5. N n NA Using a formula • N = Number of particles , ions, atoms, molecules or formula units • NA = Avogadros number • n = number of moles • n = N / NA • N = n x NA • Note on calculator  x 10 is the same as EXP or EE. DO NOT use them both • On calculator use  6.022 EXP 23

  6. Mole Calculations MM = m/n n = m/MM m = MMn m N = nNA n = N/NA n MM Factor Label! Let the units guide you

  7. Determining Molar Mass The mass of one mole is called “molar mass” E.g. 1 mol Li = 6.94 g Li • This is expressed as 6.94 g/mol • Symbol  MM What is the molar mass of CO2? Recall: Add the individual molar masses MM(NH4)3PO4 = 3(N + 4H) + P + 4O = 3N + 12H + P + 4O = 3(14.01) + 12(1.01) + 30.97 + 4(16.00) = 149.12 g/mol

  8. The same as: • Gram Molecular Mass (for molecules) • Gram Formula Mass (ionic compounds) • Gram Atomic Mass (for elements) • molar mass is just a much broader term than these other specific masses

  9. MM = m/n n = m/M m = Mn Converting Mass to Moles Example: How many moles of calcium carbonate are there in 1.5 kg? n = m/MM = 1500 g  100.09 g/mol = 15 mol Given: m CaCO3 = 1500 g MM = 40.08 + 12.01 + (3 X 16.00) = 100.09 g/mol n = 1500 g X 1 mol 100.09 g = 15 mol

  10. MM = m/n n = m/M m = Mn Converting Moles to Mass Example: What is the mass in grams of 0.346 mol of sodium sulfate? m = MMn = 142.04 g X 0.346 mol 1 mol = 49.1 g Given: n Na2SO4 = 0.346 mol MM = (2 X 22.99) + 32.06 + (4 X 16.00) = 142.04 g/mol

  11. Try These: • How much would 2.34 moles of carbon weigh? • How many moles of magnesium is 24.31 g of Mg? 28.1 grams C 1.000 mol Mg

  12. Given: m = 1.00 X 103 g MM = (12 X 12.01) + (22 X 1.01) + (11 X 16.00) = 342.34 g/mol How many sugar (sucrose, C12H22O11) molecules are there in a 1.00 kg bag? n = 1.00 X 103 g X 1 mol 342.34 g = 2.921 mol N = nNA = 2.921 mol X 6.02 X 1023 molecules 1 mol = 1.76 X1024 molecules of sugar

  13. How many carbon atoms are there in a 1.00 kg bag of sugar (sucrose, C12H22O11) ? N = 1.76 X 1024 molecules of sugar X 12 carbon atoms 1 molecule sugar = 2.11 X 1025carbon atoms

  14. Mass (g) Concentration (mol/L) g/mol Vol   Moles (mol)  6.02 X 1023 22.4  # of molecules/atoms/ions Volume (L) at STP (0˚C, 101.3 kpa)

  15. Learning check = 3.35 X 1023 atoms Cu = 1.21 X 1024 atoms K = 359 g • How many atoms of Cu are present in 35.4 g of Cu? • How many atoms of K are present in 78.4 g of K? • What is the mass of 1.20 x 1024 molecules of glucose (C6H12O6)?

  16. Learning Check! 78.1 g O2 1 mol O2 6.02 X 1023molecules O2 2 atoms O 32.0 g O2 1 mol O2 1 molecule O2 How many atoms of O are present in 78.1 g of oxygen?

  17. Measuring volume MOLAR VOLUME, Vm Volume occupied by 1 mole of any gas 22.4 L at STP (standard temperature and pressure) at 0°C and 1 atmosphere/ 103kPa (kilopascals) 24.8 L at SATP Standard Ambient Temperature and Pressure ( 20oC and 1 atmosphere )

  18. HOMEWORK Finish Grams-Mole Worksheet Mole Worksheet – Due Tuesday, April 9th

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