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CHEMICAL QUANTITIES

CHEMICAL QUANTITIES. Measuring Matter. Count Weigh Volume Each of these measurements is related to a single quantity called the “mole”. The Mole. A mole is a convenient standard quantity used to count representative particles . WHY?

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CHEMICAL QUANTITIES

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  1. CHEMICAL QUANTITIES

  2. Measuring Matter • Count • Weigh • Volume • Each of these measurements is related to a single quantity called the “mole”

  3. The Mole • A mole is a convenient standard quantity used to count representative particles. WHY? because …. atoms and molecules are so tiny, chemists use this counting unit called the mole. • it represents 6.02 x 1023 molecules or atoms or particles

  4. Representative particles: • the type of particle that make up a substance substance representative particles • elements  atoms • Molecular compounds  molecules • Ionic compounds  formula units

  5. Just as a dozen is always 12, a mole is always 6.02 x 1023. • This is called Avogadro’s number because Amedeo Avogadro came up with the idea!! • Who is he, you ask?.....

  6. Amedeo Avogadro • Was a lawyer and scientist (physics) • In 1811 proposed that equal volumes of all gases contain the same number of molecules • How many? Good question!......

  7. The number of molecules in 1 mole of gas is known to be6.022 x 1023 • He was right and so we now apply this to all molecules (not just gases).

  8. The mole is so important to chemistry that we actually haveNational Mole Day. It is every October 23 from 6:02 in the morning until 6:02 in the evening.

  9. HOW DO YOU CELEBRATE MOLE DAY?????

  10. Better ideas……….! Posters! Activities!

  11. Just imagine…. • If you had a mole of dollars ($6.022 x 1023) and you spent $1 billion every second of every minute of every hour of every day for 70 years…. • You would have spent less than 1% of your money! WOW!

  12. Examples • 1 mole of carbon = 6.022 x 1023 C atoms. • 1 mole of water = 6.022 x 1023 H2O molecules. • 1 mole of sodium chloride = 6.022 x 1023 NaCl formula units. • 1 mole of glucose = 6.022 x 1023 C6H12O6 molecules. • Pretty simple, eh?

  13. Converting from moles to Representative particles multiply by 6.022 x 1023 MOLES REPRESENTATIVE divide by 6.022 x 1023 PARTICLE

  14. You try it…. How many moles of magnesium are 3.01x 1022 atoms of Mg? Answer: 3.01x 1022 atoms 6.02 x 1023 atoms/mol = 0.500 x 10-1 = 5.00 x 10-2 mol Mg

  15. Practice! • Do problems #5 - 8 on page 51-52

  16. If you want the number of atomsin a mole of a compound… • you must know how many atoms are in the compound • Ex: how many atoms are in 1 mole of CO2? 1 mol X 6.022 x 1023 atoms/molX 3 atoms = 18.06 x 1023atoms = 1.81 x 1024atoms

  17. If you want the number of ionsin a mole of a compound… • you must know how many ions are in the compound • Ex: how many F- ions are in 1.46 mole of AlF3? 1.46 mol X 6.022 x 1023 formula units/mol X 3 F-ions = 26.3676 x 1023 F-ions = 2.64 1024 F-ions

  18. Do problems #9 - 11 On page 52

  19. Converting from representative particles reverses the process • Atoms, molecules, formula units are divided by Avogadro’s number to get the number of moles!

  20. How many moles are present in a sample of 5.83 x 1024molecules ofCO2 ? • 5.83 x 1024molecules ofCO2 6.02 x 1023 molecules /mol = 0.984x 101 mol of CO2 9.84mol of CO2

  21. Turn to page 53 Answer questions #12-15

  22. New Stuff……

  23. Representative Particles Multiply by 6.02x1023 Divide by 6.02x1023 Moles Divide by molar mass Multiply by molar mass Mass

  24. Molar Mass • Molar mass is the mass in grams of one mole of any element or compound. • The units for molar mass are g/mol • It can refer to atoms,molecules or formula units. • Huh?

  25. Molar Mass • Gram atomic mass……used for elements • Gram molecular mass….used for molecules • Gram formula mass.....used for ionic compounds All of these can be referred to as gram formula mass or molar mass …………..…what?!

  26. Gram Atomic Mass (gam) is the mass in grams of an atom = 1gam • Numerically it is equal to its atomic mass (you know…on the periodic table!) • Ex: 1mol S = 32.1g = 1gam S • 1mol Hg = 200.6g = 1gam Hg • 1mol Fe = 55.8g = 1gam Fe

  27. Example: Molar mass of carbon (aka gram atomic mass) is the mass of one mole of carbon, which would be 12.01 g/mol (refer to atomic mass of C on periodic table). • What would be the molar mass of He? • What would be the molar mass of Ba?

  28. Gram Molecular Mass (gmm) is the mass in grams of the atoms which make up the molecule Ex: 1mol SO3 = 32.0g + 3(16.0g) = 80.1g = 1gmm 1mol C6H4Cl2 = 6(12.0g) + 4(1.0g) + 2(35.5g) = 147.9g = 1gmm

  29. Molar mass of water (aka gram molecular mass) would be the mass of one mole of water………. which we find by adding up the atomic masses of each element in the molecule. Molar mass (H2O) = 2 x 1.01 = 2.02 1 x 16.0 = 16.0 18.02g/mol • What is the molar mass of sulfuric acid? H2SO4 = (2 x 1.01) + 1(32.0) + 4(16.0) = 50.01g/mol

  30. Gram Formula Mass (gfm) • is the mass in grams of the ions which make up the ioniccompound • Examples: • 1mol potassium iodide (KI) 39.1g + 126.9g = 166.0g = 1gfm KI • 1mol ammonium carbonate (NH4)2CO3 2(14.0g) + 8(1.0g) + 12.0g + 3(16.0g) = 96.0g = 1gfm (NH4)2CO3

  31. All solids, liquids and gases can be converted from mass to moles and vice versa. • From mass to moles: divide by molar mass • From moles to mass: multiply by molar mass multiply by molar mass MOLES MASS divide by molar mass

  32. EXAMPLE: • What is the mass of 4.2 mol of silver nitrate? • From moles to mass…… Multiply by molar mass • Molar mass = • AgNO3 = (107.87) + (14.01) + 3(16.00) = 169.88 g/mol • ANSWER: • Mass = 4.2 mol x 169.88g/mol = 713.5g

  33. Rasputin! Ever hear of him….?

  34. If his murderers had calculated the correct quantity of potassium cyanide, they could have killed him with much less effort….

  35. HCl + KCN  HCN + KClhydrochloric acid potassium cyanide hydrocyanic acid potassiun chloride However, they would have had to know about his unique medical condition first……. HCl + KCN  KCN + HCl hydrochloric acid potassium cyanide potassium cyanide hydrochloric acid KCN  KCN potassium cyanide potassium cyanide

  36. See…….. chemistry is useful in everyday life!

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