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The Mole / Molar Mass and Molecular Formulas

CHEM 108. The Mole / Molar Mass and Molecular Formulas. Moles & Mass. How big is a mole? (Not the animal, the other one.) - Daniel Dulek. https://www.youtube.com/watch?v=TEl4jeETVmg. The Mole.

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The Mole / Molar Mass and Molecular Formulas

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  1. CHEM 108 The Mole / Molar Mass and Molecular Formulas

  2. Moles & Mass How big is a mole? (Not the animal, the other one.) - Daniel Dulek https://www.youtube.com/watch?v=TEl4jeETVmg

  3. The Mole • Definition: The numberof carbon atoms in exactly 12 grams of pure 12C. The numberequals 6.02  10 23atoms. • 1 mole = 6.02  10 23units of anything • 6.02  10 23“units” of atoms, people, ants, stars, $$$s, etc., etc. = 1 mole There are about 7.4 billion people in the world. How many moles of people are there?

  4. There are about 7.4 billion people in the world. How many moles of people are there? • 1 mole = 6.02  10 23 units of anything • 6.02  10 23 people = 1 mole 7.4 x 10 9 people / 6.02 x 10 23 people / 1 mol = 1.2 x 10 -14 mol

  5. Avogadro’s Number Avogadro’s number equals 1 mole….which equals 6.022  1023 “units” How many molecules are there in one half mole of oxygen? 3.011  1023 molecules of oxygen

  6. Calculate the number of atoms of silicon in 0.367 moles of silicon. What do you need ? Avogadro’s Number 1 mole = 6.02 x 10 23 atoms 0.367 mol x6.02 x 10 23 atoms / 1 mol = 2.21 x 10 23 atoms Si What do you get if you divide an avocado into 6.02 x 10 23 pieces? guaca-mole!

  7. Counting by Weighing 12 red marbles @ 7g each = 84g 12 yellow marbles @ 4g each=48g 55.85g Fe = 6.022 x 1023 atoms Fe 32.07g S = 6.022 x 1023 atoms S Consult the Periodic Table

  8. Relative Masses of 1 Mole CaCO3 Name? 100.09 g Oxygen 32.00 g Copper 63.55 g Water 18.02 g 1 mole of an “ideal” gas equals 22.4 Liters. (A balloon diameter of 35 cm.) What is the volume of 1 mole of water?

  9. Atomic and Molecular WeightsMass Measurements • 1H weighs 1.6735 x 10-24 g and 16O 2.6560 x 10-23 g. • DEFINITION: mass of 12C = exactly 12 amu. • Using atomic mass units: • 1 amu = 1.66054 x 10-24 g • 1 g = 6.02214 x 1023 amu

  10. Atomic and Molecular Weights • Formula Weight a.k.a. Molecular Weight • Formula weights (FW): sum of Atomic Weights (AW) for atoms in formula. • FW (H2SO4) = 2AW(H) + AW(S) + 4AW(O) • = 2(1.0 amu) + (32.0 amu) + 4(16.0) • = 98.0 amu

  11. Atomic and Molecular Weights • Molecular weight (MW) is the weight of the molecular formula in amu. • MW of sugar (C6H12O6 ) = ? • MW = 6(12.0 amu) + 12(1.0 amu) + 6(16.0 amu) • = 180 amu

  12. Molar Mass • A substance’s molar massis the mass in grams of one mole of the element or compound. (Equals the formula weight: atomic or molecular weight in grams) Molar Mass CO2 = ? C = 12.01 grams per mole (g/mol) O = 16.00 grams per mole (g/mol) CO 2 = 44.01 grams per mole (g/mol) 12.01 + 2(16.00) = 44.01

  13. Calculate the molar mass of potassium phosphate. What do you need ? 1) Formula of potassium phosphate: K3PO4 2) Atomic Weights (molar mass) K = 39.10, P = 30.97, O = 16.00 3(39.10) + 30.97 + 4(16.00) = 212.27 g/mol

  14. Calculate the molar mass of magnesium sulfate. What do you need ? 1) Formula of magnesium sulfate: MgSO4 2) Atomic Weights (molar mass) Mg = 24.31, S = 32.07, O = 16.00 24.31 + 32.07 + 4(16.00) = 120.38 g/mol

  15. Calculate the mass in grams of 4.00 moles of sulfur. What do you need ? Atomic Weight sulfur (S) = 32.07 (molar mass) = 32.07 g/mol 4 mol sulfur x 32.07 g/mol sulfur = 128.3 g

  16. Calculate the mass in grams of 0.100 moles of magnesium sulfate hydrate. What do you need ? Atomic Weight MgSO4. H2O = 120.38 + 18.02 (molar mass) = 138.40 g/mol 0.100 mol MgSO4. H2O x 138.40 g/mol MgSO4. H2O = 13.84 g

  17. Calculate the mass in grams of 0.100 moles of magnesium sulfate tetrahydrate. What do you need ? Atomic Weight MgSO4. 4H2O = 120.38 + 4(18.02) (molar mass) = 192.44 g/mol 0.100 mol MgSO4. H2O x 192.44 g/mol MgSO4. H2O = 19.244 g

  18. Percent Composition • Mass percent of an element: • For iron in (Fe2O3), iron (III) oxide = ? Which iron ore would you buy: one high in Fe2O3 or one high in FeO, Iron (II) oxide? 55.84 / 71.84 x 100 = 77.7%

  19. Percent Composition Calculate the percentage composition for all the elements in an alkaloid with the molecular formula C10H14N2. What do you need ? Molar mass C10H14N2 C = 12.01, H = 1.01, N = 14.01 10(12.01) + 14(1.01) + 2(14.01) = 162.26 g/mol 120.1g/mol 14.14 g/mol 28.02 g/mol 120.1/162.2614.14/ 162.2628.02/ 162.26 x 100 = x 100 = x 100 = 74.02%8.71%17.27%

  20. Percent Composition Calculate the percent water in magnesium sulfate pentahydrate. What do you need ? Atomic Weight MgSO4. 5H2O = 120.38 + 5(18.02) (molar mass) = 210.46 g/mol Calculate the percent water in “Epsom” salt, magnesium sulfate heptahydrate What do you need ? Atomic Weight MgSO4. 7H2O = 120.38 + 7(18.02) (molar mass) = 246.49 g/mol 5(18.02)/210.46 7(18.02)/ 246.49 x 100 = x 100 = 42.8%51.2%

  21. Hydrate: % Water EPSOM SALT

  22. What’s My Formula? Unknown Sample Salt Unknown Sample Salt Unknown Sample Salt Unknown Sample Salt EXPERIMENTAL: CALCULATIONS:

  23. What’s My Formula? An experimental value is nearly impossible to have equal the calculated value due to inherent errors in conducting any experiment. A quantitative comparison (“% Yield”) is used to measure the efficiency (similar to “accuracy”) of any procedure in yielding a “product” (on the right of an equation) versus the calculated (theoretical) amount of the product based on the reactant(s) (on the left of the equation) for any chemical reaction. Unknown Sample Salt EXPERIMENTAL: CALCULATIONS:

  24. What’s My Formula? “% Yield” is used to measure the efficiency (similar to “accuracy”) of any procedure in yielding a “product” (on the right of an equation) versus the calculated (theoretical) amount of the product based on the amount of reactant(s) (from the left of the equation) for any chemical reaction using the relative number of moles of each. % Yield = actual grams of product / theoretical (calculated) grams of product x100 For example, heating 10.00 g of sodium bicarbonate and actually obtaining g of sodium carbonate Reactant = 10.00 gMolar Mass = 84.00 g/mol Product = ? g (Theoretical) Molar Mass = 105.99 g/mol

  25. Theoretical Mass (Yield) Calculations Reactants Products grams (Reactant) grams (Product) Moles Molar Mass grams (P) 1 mol (R) grams (R) ? mol (P) ? grams (P) ? mol (R) grams (R) 1 mol (P) (Divide) Mass (R) (Multiply) Mass (P) by Molar "Gatekeepers” from Balanced reaction by Molar

  26. QUESTION • A synthetic reaction produced 2.45g of Ibogaine, C20H26N2O, a natural product with strong promise in treating heroin addiction, the calculated theoretical yield was 3.05g, what is the % yield? A) 19.7% B) 39.4% C) 80.3% D) 160.6%

  27. ANSWER • If a reaction produced 2.45g of Ibogaine, C20H26N2O, a natural product with strong promise in treating heroin addiction, and the theoretical yield was 3.05g, what is the % yield? • 19.7% B) 39.4% C) 80.3% D) 160.6% % yield = 2.45g / 3.05g x 100 = 80.3%

  28. Formulas: Dalton’s Law • Dalton’s law of multiple proportions: When two elements form different compounds, the mass ratio of the elements in one compound is related to the mass ratio in the other by a small whole number.

  29. Formulas: Multiple Proportions http://chemconnections.org/general/movies/multiple-proportions.MOV

  30. Formulas & Multiple ProportionsComponents of acid rain, SO2(g) and SO3(g) • Compound A contains: 1.000 g Sulfur & 1.500 g Oxygen • Compound B contains: 1.000 g Sulfur & 1.000 g Oxygen • Mass ratio A: 1 to 1.5; Mass ratio B: 1 to 1 • MUST adjust for atomic mass differences: AW sulfur is 2x the AW oxygen; therefore the oxygen ratios are 2x sulfur. • S1O3 and S1O2 respectively

  31. Compounds with the Same Formula [ eg. C9H8O4 ] Aspirin 4-Hydroxyphenylpyruvic acid Dihydroxycinnamic acids: Caffeic acid (3,4-dihydroxycinnamic acid) Umbellic acid (2,4-dihydroxycinnamic acid) 2,3-Dihydroxycinnamic acid 2,5-Dihydroxycinnamic acid 3,5-Dihydroxycinnamic acid

  32. Molar Comparisons of Analgesics Moles : Doses (mmol/dose) Which analgesic has the most biologically active ingredient based on millimoles per dose (mmol/dose)? 5.0 g of each would produce the following number of doses: Formula Doses mmol/dose Aspirin C9H8O4 15.4 Ibuprofen C13H18O2 25 Naproxen Sodium C14H13O3Na 22.7 Acetaminophen C8H9NO2 5 28 mmol Molar Mass Aspirin = 180.1 g/mol 5.0 g / 180.1 g/mol = 0.028 mol = 28 mmol

  33. Moles / Molar Mass and Molecular Formulas QUIZ QUESTIONS Complete the Nomenclature Tutorial before beginning Quiz http://chemconnections.org/general/chem108/Nomenclature.htm

  34. QUESTION Strychnine is often the poison of choice in murder mysteries. It has a formula of C21H22N2O2. How many moles of carbon atoms and oxygen atoms are there in one mole of strychnine? • 21 mol of carbon atoms and 1 mol of oxygen atoms • 21 mol of carbon atoms and 2 mol of oxygen atoms • 22 mol of carbon atoms and 21 mol of oxygen atoms • 2 mol of carbon atoms and 2 mol of oxygen atoms

  35. QUESTION How many atoms of silicon are there in 0.367 moles of silicon? A) 6.10 x 10-25 atoms Si B) 2.21 x 10 23 atoms Si C) 2.21 atoms Si D) 1.64 x 10 24 atoms Si

  36. QUESTION Potassium phosphate and sodium phosphate is a combination medicine used to make urine more acidic to help prevent kidney stones. What is the molar mass of potassium phosphate? a) 134 g/mol b) 86.07 g/mol c) 134.07 g/mol d) 212.27 g/mol

  37. QUESTION Sulfur is derived from the Latin word sulpur. The Greek word for sulfur, θεῖον, which is the source of the international chemical prefix thio-. Sulfur is prominent in volcanic areas like Lassen National Park, which by the way stinks! What is the mass in grams of 4.00 moles of sulfur? A) 128 g B) 128.3 g C) 12.5 g D) 0.125 g

  38. QUESTION

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  40. QUESTION

  41. QUESTION

  42. QUESTION Morphine, derived from opium plants, relieves pain and is addictive. It’s formula is C17H19NO3. What percent, by mass, is the carbon in this compound? 42.5% 27.9% 71.6% This cannot be solved until the mass of the sample is given.

  43. QUESTION Nearly 35 million smokers want to quit each year. Unfortunately, more than 85 percent of those who try to quit relapse, most within a week. Nicotine use is more difficult to withdraw from than heroin. What is the percent composition for nicotine, C10H14N2? A) 64.14% C, 14.04% H, 21.82% N B) 74.017 % C, 8.714 % H, 17.27 % N C) 74.02 % C, 8.71 % H, 17.27 % N D) 44.43 % C, 3.74 % H, 51.83 % N Nicotiana tobacum

  44. Quiz QUESTIONS/ Answers

  45. QUESTION Strychnine is often the poison of choice in murder mysteries. It has a formula of C21H22N2O2. How many moles of carbon atoms and oxygen atoms are there in one mole of strychnine? • 21 mol of carbon atoms and 1 mol of oxygen atoms • 21 mol of carbon atoms and 2 mol of oxygen atoms • 22 mol of carbon atoms and 21 mol of oxygen atoms • 2 mol of carbon atoms and 2 mol of oxygen atoms

  46. Answer Strychnine is often the poison of choice in murder mysteries. It has a formula of C21H22N2O2. How many moles of carbon atoms and oxygen atoms are there in one mole of strychnine? • 21 mol of carbon atoms and 1 mol of oxygen atoms • 21 mol of carbon atoms and 2 mol of oxygen atoms • 22 mol of carbon atoms and 21 mol of oxygen atoms • 2 mol of carbon atoms and 2 mol of oxygen atoms

  47. QUESTION How many atoms of silicon are there in 0.367 moles of silicon? A) 6.10 x 10-25 atoms Si B) 2.21 x 10 23 atoms Si C) 2.21 atoms Si D) 1.64 x 10 24 atoms Si

  48. Answer How many atoms of silicon are there in 0.367 moles of silicon? A) 6.10 x 10-25 atoms Si B) 2.21 x 10 23 atoms Si C) 2.21 atoms Si D) 1.64 x 10 24 atoms Si

  49. QUESTION Potassium phosphate and sodium phosphate is a combination medicine used to make urine more acidic to help prevent kidney stones. What is the molar mass of potassium phosphate? a) 134 g/mol b) 86.07 g/mol c) 134.07 g/mol d) 212.27 g/mol

  50. Answer Potassium phosphate and sodium phosphate is a combination medicine used to make urine more acidic to help prevent kidney stones. What is the molar mass of potassium phosphate? a) 134 g/mol b) 86.07 g/mol c) 134.07 g/mol d) 212.27 g/mol

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