Chapter6

Chapter6

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Unformatted text preview: shuttle is a mixture of ammonium perchlorate and aluminum powder. Upon ignition, one of the reactions that occurs is: NH4ClO4(s) + Al(s) → Al2O3(s) + N2(g) + HCl(g) + H2O(g) • Balance this skeletal equation 6NH4ClO4(s) + 10Al(s) → 5Al2O3(s) + 3N2(g) +6 HCl(g) + 9H2O(g) 2. If Buzz Aldrin has 20 moles of Al powder and Neal Armstrong has 13 moles of ammonium perchlorate, which reactant will be limiting? Al • How many moles of the excess reactant will be left over if the reaction goes to completion? 1 mole of NH4ClO4 will be left. • Identify the oxidizing agent and the reducing agent in this reaction Al is the reducing agent, NH4ClO4 is the oxidizing agent14 and the reducing6AagentJ. (NH4+Sans oxidized, ClO4- is reduced) Chem Michael Sailor, UC i Diego Problem: Hess’ Law applied to the Thermite reaction Fe2O3(s) + 2Al(s) → 2Fe(s) + Al2O3(s) Calculate the standard change in enthalpy for the Thermite reaction, given the thermochemical data on the next page. 24 Chem 6A Michael J. Sailor, UC San Diego Data: ΔH° (Fe2 O3(s) ) = −826kJ/mol f ΔH° (Al 2 O3(s) ) = −1676kJ/mol f ΔH° (Fe(s) ) = 0kJ/mol f ΔH° (Al (s) ) = 0kJ/mol f 2Al (s) + Fe2 O3(s) → 2Fe(s) + Al 2 O3(s) ΔH° = ∑ np ΔH° (products) - ∑ nr ΔH° (reactants) reaction f f ΔH° reaction = 2(0) + (−1676) − [2(0) + (−826)] = −850kJ 25 Chem 6A Michael J. Sailor, UC San Diego Solution: ΔH° (Fe2 O3(s) ) = −826kJ/mol f ΔH° (Al 2 O3(s) ) = −1676kJ/mol f ΔH° (Fe(s) ) = 0kJ/mol f ΔH° (Al (s) ) = 0kJ/mol f 2Al (s) + Fe2 O3(s) → 2Fe(s) + Al 2 O3(s) ΔH° = ∑ np ΔH° (products) - ∑ nr ΔH° (reactants) reaction f f ΔH° reaction = 2(0) + (−1676) − [2(0) + (−826)] = −850kJ 26 Chem 6A Michael J. Sailor, UC San Diego Solution: ΔH° (Fe2 O3(s) ) = −826kJ/mol f ΔH° (Al 2 O3(s) ) = −1676kJ/mol f ΔH° (Fe(s) ) = 0kJ/mol f ΔH° (Al (s) ) = 0kJ/mol f 2Al (s) + Fe2 O3(s) → 2Fe(s) + Al 2 O3(s) ΔH° = ∑ np ΔH° (products) - ∑ nr ΔH° (reactants) reaction f f ΔH° reaction = 2(0) + (−1676) − [2(0) + (−826)] = −850kJ 27 Chem 6A Michael J. Sailor, UC San Diego...
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This note was uploaded on 11/16/2011 for the course CHEM 6A taught by Professor Pomeroy during the Spring '08 term at UCSD.

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