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Lesson 10 The Mole

Lesson 10 The Mole. 10.1 – Atomic, Molecular, & Formula Masses; Percent Composition. 10.2 – The Mole & Avogadro’s Number 10.3 – Molar Mass & Mole-Mass Conversions. Anything in black letters = write it in your notes (‘knowts’).

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Lesson 10 The Mole

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  1. Lesson 10 The Mole 10.1 – Atomic, Molecular, & Formula Masses; Percent Composition. 10.2 – The Mole & Avogadro’s Number 10.3 – Molar Mass & Mole-Mass Conversions Anything in black letters = write it in your notes (‘knowts’)

  2. 10.1 – Atomic, Molecular, & Formula Masses; Percent Composition. 3 similar but slightly different terms… Atomic Mass - mass of an atom (a.m.u.) 1 C atom = 12.011 a.m.u. Molecular Mass - mass of a molecule (a.m.u.) 1 CO2 molecule = 12.011 + 2(15.999) = 44.009 a.m.u. Formula Mass - mass of a formula unit (a.m.u.) 1 MgO formula unit = 24.305 + 15.999 = 40.304 a.m.u.

  3. Remember… Ionic compounds are composed of formula units. Covalent compounds are composes of molecules.

  4. Example: calculate the percent composition of oxygen in CO2

  5. Example: Which compound contains a higher percent of oxygen; CO2 or CO? Explain without calculating.

  6. 10.2 – The Mole & Avogadro’s Number A mole is a number of particles 1 mole = 6.02 x 1023 particles Avogadro’s Number A particle can be an atom, molecule, formula unit, ion, etc Mole is abbreviated as mol – no joke! Mole – latin for large structure

  7. How big is Avogadro’s Number? If you could travel at the speed of light, it would take you more than 100 billion years to travel 6.02 x 1023 miles. 6.02 x 1023 baseballs would cover the Earth to a height of several hundred miles.

  8. How big is Avogadro’s Number? A computer that can make 200 million counts per second would need almost 100 million years to count up to 6.02 x 1023 A stack of paper with 6.02 x 1023 sheets would be so tall that it would reach from here to the sun—not just once but more than a million times!

  9. How big is Avogadro’s Number? If 6.02 x 1023 dollars were divided among the 7 billion people on Earth, we would have enough money that each of us could spend a million dollars every minute, night and day, for as long as we lived an still have more than half of it left. …but where would we put all those dollars?

  10. What is the point of a mole? • What is the point of a dozen? • To count large numbers of particles easier. • Yes, the mole was created to make things EASIER! You will have to be able to measure an amount of matter and convert to moles of that substance. The number of moles really tells you the number of particles (atoms, molecules or formula units).

  11. Atomic Mass – mass of an atom (a.m.u.) Molecular Mass – mass of a molecule (a.m.u.) already know this Formula Mass – mass of a formula unit (a.m.u.) 6.02 x 1023 Molar Mass – mass of 1 mole of particles measured in grams

  12. The molar mass (in grams) equals the particle’s mass (in a.m.u.) Examples… 1 atom Na = 22.99 a.m.u. 6.02 x 1023 Na atoms (1 mol) = 22.99 g Na 1 formula unit NaCl = 58.44 a.m.u. 6.02 x 1023 NaCl formula units (1 mol) = 58.44 g NaCl 1 molecule H2O = 18.0 a.m.u. 6.02 x 1023 H2O molecules (1 mol) = 18.0 g H2O

  13. We will rarely talk about 6.02 x 1023 because it is large and inconvenient. Just say ‘1 mole’ instead of ‘6.02 x 1023’

  14. 10.3 – Molar Mass & Mole-Mass Conversions How to convert from grams to moles How to convert from moles to grams

  15. Quick Mole Quiz • Define Molar Mass. • Calculate the molar mass of CO2. • Convert 3.4 mol of CO2 into grams. • Convert 0.981 grams of CO2 into mol.

  16. Quick Mole Quiz #2 • 1. Circle which of the following in each pair contains more molecules? • 1.00 mol H2O2 or 1.00 mol H2O • 2.71 grams of CO2 or 3.45 grams of H2O • 1.00 mol CO or 6.02 x 1023 molecules of CO

  17. Quick Mole Quiz #2 • Aluminum combines with oxygen gas to form aluminum oxide. • 2. Write a balanced chemical equation for this reaction. • 3. If 2.70 grams of aluminum formed 5.10 grams of aluminum oxide, what was the mass of the oxygen that combined with the aluminum?

  18. Quick Mole Quiz #2 • 4. Convert the mass of aluminum into moles of aluminum (mol of Al) & convert the mass of oxygen in to moles of oxygen (mol of O, not mol of O2) • 5. How many more moles of oxygen atoms are there than moles of aluminum atoms? • 6. Use your answer from question 5 to determine the chemical formula for aluminum oxide. Does it agree with your balanced equation? - it should…

  19. Quick Mole Quiz #3 1 mol Fe = _______ g Fe = ____________ Fe atoms 1 mol Fe2O3 = ________ g Fe2O3 = __________ Fe2O3 formula units Convert 10.0 grams of iron into moles. Convert 10.0 grams of iron(III) oxide into moles.

  20. Lab 19 Prep 2 NaHCO3Na2CO3 + H2O + CO2 Balance the above reaction. What type of reaction is this? Calculate the molar mass of NaHCO3 Calculate the molar mass of Na2CO3

  21. Lab 19 Prep 2 NaHCO3Na2CO3 + H2O + CO2 Mass of empty evap. dish = 46.93 g Mass of dish with NaHCO3 = 55.28 g Mass of dish after heating = 52.18 g 1. Calculate the starting mass of NaHCO3 2. Calculate the mass of Na2CO3 that was produced.

  22. Lab 19 Prep 2 NaHCO3Na2CO3 + H2O + CO2 3. Convert the mass of NaHCO3 into moles 4. Convert the mass of Na2CO3 into moles

  23. Lab 19 Prep 2 NaHCO3Na2CO3 + H2O + CO2 5. If you started with 2 mol NaHCO3, how many mol of Na2CO3 would be produced? 6. How does this compare to your experimental results?

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