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To solve problems involving volumes of gases NOT at STP in chemical reactions:

To solve problems involving volumes of gases NOT at STP in chemical reactions:. Combine PV = nRT and stoichiometry. What volume of hydrogen will react w /carbon at 981 torr and 334 o C to yield 42.0 g of n-pentane? . H 2 + C. C 5 H 12. 6. 5. 42.0 g n-p. (. ). (. ).

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To solve problems involving volumes of gases NOT at STP in chemical reactions:

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  1. To solve problems involving volumes of gases NOT at STP in chemical reactions: Combine PV = nRT and stoichiometry.

  2. What volume of hydrogen will react w/carbon at 981 torr and 334oC to yield 42.0 g of n-pentane? H2 + C C5H12 6 5 42.0 g n-p ( ) ( ) = 3.5 mol H2 6 mol H2 1 mol n-p 72 g n-p 1 mol n-p P V = n R T = 135 L H2

  3. partial pressures: total pressure of gaseous mixture Dalton’s law of Partial Pressure Ptot = P1 + P2 + ... pressure that each gas would exert by itself Other equations… Total moles of gas in a mixture: ntot = n1 + n2 + … The mole fraction (X) of a gas in a mixture:

  4. 1 mol 1 mol 28.0 g 2.0 g ntot = 20.357 mol ( ( ) ) 1. Find ntot. Find the total pressure exerted by 38.0 g of carbon monoxide and 38.0 g of hydrogen in a 6.00-L container at 25oC. 2. Use PV = nRT to find P. nCO = 38 g = 1.357 mol CO nH2 = 38 g = 19.0 mol H2 = 8410 kPa

  5. mole fraction ( ( ) ) 1.357 20.357 19.0 20.357 With reference to the previous problem… What is the partial pressure exerted by each gas? The ratio of the partial pressures is the same as the mole ratio. PCO = 8410 kPa = 560 kPa (38 g CO) PH2 = 8410 kPa = 7850 kPa (38 g H2)

  6. H2O levels even reaction complete before reaction during reaction Collecting Gases over Water collected gas filled w/water, initially (w/H2O vapor, too) gas being collected gas from reaction After rxn. is complete, raise or lower collecting vessel so H2O levels inside and out are the same. In this way... Patmos = Pgas + PH2O

  7. ( ) 64.1 g 1 mol For the reaction CaC2(s) + H2O(l) C2H2(g) + CaO(s)... If 0.852 L of acetylene are collected over water at 20.0oC, find the moles of acetylene collected and the grams of calcium carbide used. The barometric pressure is 732.0 torr. 732.0 torr = PC2H2 + PH2O 17.5 torr @ 20.0oC (from p. 1111) So PC2H2 = 714.5 torr = 0.9401 atm = 0.0333 mol C2H2 From bal. eq., nCaC2 = nC2H2, so gCaC2 = 0.0333 mol = 2.13 g CaC2

  8. A B C Z 1.3 L 2.6 L 3.8 L 2.3 L 3.2 atm 1.4 atm 2.7 atm X atm Find the total pres. in container Z, assuming constant T. = 3.2 atm 1.3 L 1.81 atm 2.3 L 1.4 atm 2.6 L 1.58 atm 2.7 atm 3.8 L 4.46 atm 7.9 atm

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