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What Is a Mole?

What Is a Mole?. One mole = 6.022 x 10 23 items. A mole of atoms Or molecules. How Big is a Mole?. N=6.022x10 23 One mole of Marshmallows would cover the entire earth 12 miles high

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What Is a Mole?

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  1. What Is a Mole?

  2. One mole = 6.022 x 1023 items A mole of atoms Or molecules

  3. How Big is a Mole? • N=6.022x1023 • One mole of Marshmallows would cover the entire earth 12 miles high • One mole of marshmallows would fill the Grand Canyon and still be enough left over to displace all the water from Lake Michigan and more

  4. Moles as Conversion factors • Grams to moles • Use Molar Mass • Ex: How many moles are in 9.01 g of water? • Moles to molecules or atoms • Use Avogadro’s number • Ex: How many molecules of water are in 9.01 g of water?

  5. Using Avogadro’s number • Nicotine, a poisonous compound found in tobacco leaves, is 74.0% C, 8.65% H, and 17.35% N. It has a molar mass of 162 g/mol. • What is the molecular formula of nicotine? • The “average” cigarette in the US contains 9.0 mg of nicotine but during smoking about 90% of the nicotine is burned off. • How many molecules of nicotine are inhaled during smoking of one “average” cigarette?

  6. Molarity How would you prepare 1 liter of a 0.25 M (molar) solution of glucose (C6H12O6) (molar mass 180 g/mol)?

  7. Balancing Chemical Equations 2H2 + O2 2H2O 2 atoms hydrogen forms 2 molecules + water 1 atom oxygen

  8. Law of Conservation of Matter Matter can not be created nor destroyed. 2H2 + O2 2H2O So 2 grams of hydrogen + 1 gram of oxygen does not form 2 grams of water

  9. Balancing chemical equationsthe OHO method O - Other H- Hydrogen O- Oxygen

  10. Combustion reactions • Balance the following reactions • Methane + oxygen carbon dioxide and water • Methanol (CH3OH) burns in oxygen to form carbon dioxide and water

  11. Balance the following chemical reactions • Sodium sulfate and calcium nitrate react to form sodium nitrate and calcium sulfate • Write a balanced equation for the reaction between aqueous solutions of potassium chromate and silver nitrate. The products of the reaction are solid silver chromate and a solution of potassium nitrate

  12. Stoichiometry Moles A Moles B Grams A Moles A Moles B Moles B Grams B Grams A Moles A

  13. Stoichiometry Mole to Mole • Chlorine reacts with sodium to form sodium chloride. How many moles of sodium chloride are produced from 2.25 moles of chlorine? • A 0.50 mol sample of solid KClO3 decomposes to give solid KCl and gaseous oxygen. How many moles of KCl will be produced?

  14. Stoichiometry mass to mass • Phosphorus reacts with oxygen to produce diphosphoruspentoxide. What is the mass of product formed from 20.0 g phosphorus? • Aluminum reacts with sulfur to produce aluminum sulfide. How many grams of sulfur are required to react with 4.80 grams of aluminum?

  15. Limiting Reactant • for reactions with multiple reactants, it is likely that one of the reactants will be completely used before the others • when this reactant is used up, the reaction stops and no more product is made • the reactant that limits the amount of product is called the limiting reactant • sometimes called the limiting reagent • the limiting reactant gets completely consumed • reactants not completely consumed are called excess reactants • the amount of product that can be made from the limiting reactant is called the theoretical yield

  16. Put more simply: What is the theoretical yield of hamburgers in the above reaction?

  17. O O O O H H H H + + + C C + H H O O O O H H Limiting and Excess Reactants in the Combustion of Methane CH4(g) + 2 O2(g) ® CO2(g) + 2 H2O(g) • Our balanced equation for the combustion of methane implies that every 1 molecule of CH4 reacts with 2 molecules of O2

  18. O O O O O O O O H H H H H H H H H H C C C C C ? H H H H H + H H H H H O O O O O O O O Limiting and Excess Reactants in the Combustion of Methane • CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g) • If we have 5 molecules of CH4 and 8 molecules of O2, which is the limiting reactant?

  19. ICE Chart CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g)

  20. Stoichiometry (sample problems) • 3 CS2 + 6 NaOH 2 Na2CS3 + Na2CO3 + 3 H2O • If 1.00 mol of CS2 reacts with 1.00 mol NaOH how many moles of each product are formed? • How many grams of Na2CS3 are produced in the reaction of 88.0 mL of liquid CS2 (d=1.26g/mL) and 3.12 mol NaOH

  21. Stoichiometry(sample problems) • What mass of H2 is produced by the reaction of 2.14 g Al with 75.0 mL of 2.90 M HCl? • 2 Al + 6HCl  3H2 + 2 AlCl3

  22. Percent yield

  23. Percent yield • Chlorobenzene, a starting material in the production of aspirin and other compounds is prepared from benzene by the following reaction • C6H6(l) + Cl2(g)  C6H5Cl(l) + HCl(g) • benzene chlorobenzene • A 10.0 kg sample of benzene treated with excess chlorine gas yields 10.4 kg of chlorobenzene. Calculate the % yield.

  24. Actual and theoretical yields • A laboratory manual calls for 13.0 g C4H9Br, 21.6 g NaBr, and 33.8 g H2SO4 as reactants in this reaction • C4H9Br + NaBr + H2SO4 C4H9Br + NaHSO4 + H2O • A student following these directions obtains 16.8 g C4H9Br. What are (a) the theoretical yield (b) the actual yield and (c) the percent yield in the reaction?

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