# thermo - P etrucci 9th ed Problem set #2...

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Petrucci 9th ed Problem set #2 Thermodynamics:Page 1 of 2 Petrucci 9th Edition problem set #2: Themochemistry 7.6 Treat the steel as the system and the water as the surroundings steel water q + q = 0 steel steel final initial steel water water final initial water m c (T -T ) + m c (T -T ) = 0 assuming the density of water is 1 g cm -1 steel m X 0.50 X (51.5 - 183) + 125 X 4.184 X (51.5 - 23.2) = 0 steel m = 2.2 x 10 g 2 The accuracy of this method is limited by the precision of the specific heat of steel (only given to 2 significant figures) and our assumption that no heat is lost to the surroundings during this process. The mass of the stainless steel could be determined far more accurately by weighing it on an analytical balance. 7.17 We need to know which gas is in excess moles of hydrogen = 90.0 g/2.016 g mol = 44.64 mol -1 moles of oxygen = 90.0 g/31.999 g mol = 2.813 mol -1 22 2 we need 2 moles of H per mole of O so we are limited by the amount of O from the stoichiometry 2 0.5 mole of O produces 241.8 kJ of heat 2 2.813 mole of O produces: (2.813/0.5) X 241.8 kJ = 1.36 x10 kJ 3 c 7.35

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## This note was uploaded on 10/27/2009 for the course CHEMISTRY 210064 taught by Professor Hastie during the Fall '09 term at York University.

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thermo - P etrucci 9th ed Problem set #2...

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