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  1. Ch 9 SToichioMetry Final

  2. 100 ChemEqnsHow is bromine written in a chemical equation?Answer

  3. ChemEqns100 Br2 It is diatomic

  4. 200 ChemEqnsWrite a balanced equation, with phases, for the formation of carbon monoxide from its elements.Answer

  5. ChemEqns200 2C(s) + O2(g) 2CO(g)

  6. 300 ChemEqnsTo balance a chemical equation, you may change _______ but you may not change ______Answer

  7. ChemEqns 300 To balance a chemical equation, you may change _coefficients_ but may not change _subscripts or formulas_

  8. 400 ChemEqnsWrite a balanced chemical equation for the combustion of heptane, C7H16AnswerAll Play!!!

  9. ChemEqns400 Answer 1C7H16 +11O2 7CO2 +8H2O

  10. 500 ChemEqns Write the balanced equation, with phases, for the reaction between silver nitrate and copper. AnswerAll Play!!!!

  11. ChemEqns500 Answer 2AgNO3(aq) + Cu(s) 2Ag(s) + Cu(NO3)2(aq)

  12. 100 LabWhat observation allows you to determine that a reactant is the Limiting Reactant?Answer

  13. Lab100 Answer It is gone – used up. It may not always be possible to observe this, for instance if it is in the aqueous phase.

  14. 200 Lab What observation allows you to determine that a reactant is the Excess Reactant? What is the Excess Reactant in most combustions? Explain. Answer

  15. Lab 200 Answer • Some of the excess reactant is left over after the reaction stops. • Oxygen is the ER in combustions b/c it comes from the air and is unlimited.

  16. 300 LabExplain why a candle loses mass as it burns.Answer

  17. Lab300 Answer Products are CO2 and H2O gases that escape into the air during combustion

  18. 400 LabIn the AgNO3 Lab, which of the following experimental errors would give a ratio of 1.10 molAg/1mol AgNO3?A. Running more than 30 min.B. Insufficient washing/decantingC. Weighing Ag while it is still wet.D. Impure reactantsAnswer All Play!!

  19. Lab400 Answer • B and C will increase mass of Ag insufficient washing leaves some copper nitrate in with Ag. Weighing wet gives mass of Ag + water • A does not have an effect b/c the reaction STOPS when limiting reactant is used up. More time does not give more product after LR is gone. • D decreases mass of product

  20. 500 LabWhat was the purpose of washing and decanting the silver after the silver nitrate reaction had finished?Answer

  21. Lab500 Answer To purify the Ag by rinsing away the water soluble product, Cu(NO3)2.

  22. 100 LR/TYWhat is the molar mass, to 2 decimals, of Cu(NO2)2?Answer All Play!

  23. LR/TY 100 Answer 155.57 g/mol

  24. 200 LR/TY • Write the mole ratio of phosphorus to fluorine in the following equation P4+ 6F2 4PF3 Answer All Play!!!

  25. LR/TY200 1mole P4 6mol F2

  26. 300 LR/TYStoichiometry predicts 2.55 g of Ag product. Data gives the following: empty beaker = 45.68 gbeaker plus Ag = 47.68 gWhat is % Yield? Answer All Play!!!

  27. LR/TY 300 Answer % Yield = 2.00gx 100 2.55 g = 78.4%

  28. 400 LR/TYList 4 reasons, other than human error, why yield is usually less than 100%.All Play!!Answer

  29. LR/TY 400 Answer See your class notes!

  30. 500 LR/TYIf 5.00 g of S8 and 10.00 g of Cu are combined, what is the theoretical yield of product?16Cu + S8 8Cu2SAnswer All Play!!

  31. LR/TY 500 Answer 5.00 g of S8 gives 0.155910 mol Cu2S 10.00 g of Cu gives 0.078678 mol Cu2S Cu is the Limiting Reactant 0.078678 molCu2S x 159.17g/mol = 12.52 g Cu2S

  32. 100 Stoichiometry What two types of conversion factors are needed for stoichiometry calculations?Answer

  33. Stoichiometry 100 Answer • Mole Ratio from the balanced equation • Molar Mass

  34. 200 StoichiometryWhat part of a balanced equation gives the numerical part of the mole ratio?Answer All Play!!

  35. Stoichiometry 200 Answer Coefficients

  36. 300 StoichiometryS + 3F2 SF6What mass of fluorine produces 0.75 moles of SF6?Answer All Play!!

  37. Stoichiometry 300 Answer S + 3F2 SF6 ?g F2 = 0.75 mol SF6 x 3molF2x 38.00 g F2 1 1mol SF6 1mol F2 = 85.5 ͌ 86 g F2

  38. 400 StoichiometryS + 3F2SF6What mass of sulfur reacts with 3.80 g of Fluorine?Answer All Play!

  39. Stoichiometry 400 Answer S + 3F2 SF6 ?g S = 3.80g F2 x 1mol F2 x 1mol S x 32.07gS 1 38.00g F2 3molF2 1mol S =1.07 g S

  40. 500 Stoichiometry S + 3F2SF6What is the theoretical yield of SF6 when 3.00 mol of F2 reacts with excess sulfur?Answer All Play!!

  41. Stoichiometry 500 Answer S + 3F2 SF6? g SF6 = 3.00mol F2 x 1molSF6 x 146.07g SF6 1 3mol F2 1mol SF6 = 146 g SF6

  42. 100 PotpourriA balanced equation has the same number of ______ on both sides of the arrow.Answer

  43. Potpourri 100 A balanced equation has the same number of each type of atoms on both sides of the arrow.

  44. 200 PotpourriThe maximum amount of product possible in a chemical reaction is ________.Answer All Play!!

  45. Answers for Potpourri 200 The maximum amount of product possible in a chemical reaction is theoretical yield.

  46. 300 Potpourri • How many questions must King Arthur and his Knights each answer in order to cross the Bridge of Death and keep from being cast into the Gorge of Eternal Peril? All Play! Answer

  47. Potpourri 300 Answer Three (3) (III)

  48. 400 PotpourriExplain why the product of burning Iron weighs more than the reactant Iron (steel wool)Answer

  49. Potpourri 400 Answer Only one reactant, Fe, is weighed. O2 cannot be weighed. After reaction, Fe atoms are bonded to Oxygen atoms from the air, so you are weighing both Fe and O

  50. 500 PotpourriBalance and add phase scripts to the following equation.Fe2O3 + CO Fe + CO2Answer All Play!!