#1 Hess's Law

# #1 Hess's Law - Aaron King 660556233 Section 1 February 6...

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Aaron King 660556233 Section 1 February 6, 2008 #1 Hess’s Law Data: Solution Added T i T f ∆T 1 2.00M HCl 2.00M NaOH 25.19°C 38.39°C 13.20°C 2 2.00M HCl 0.1639g Mg 20.12°C 27.27 C 7.15 C 3 3.00M HCl 0.5023g MgO 20.93°C 24.76 C 3.83°C 1. = - ∆Trxn Tf Ti = . ° - . ° ∆Trxn 38 39 C 25 19 C = . ° ∆Trxn 13 20 C 2. = qH2O massH2OCpH2O∆TH2O = . . . . qH2O 1 00gmL100 0mL4 18Jg℃13 20℃1kJ1000J = . qH2O 5 52kJ =- - qcal qH2O qrxn =- . - . - . qcal 0 100mol 58 3kJmol 5 52kJ = . qcal 0 31kJ = Cpcal qcal∆T = . . Cpcal 0 31kJ13 20℃ = . / Cpcal 23 5J ℃ The value should be positive because the energy released by the water was greater than the energy released by the whole reaction. Also the reaction was exothermic. 3.

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King 2 , = qrxn 1 mc∆T , = . . - . qrxn 1 100g4 18Jg℃27 27℃ 20 12℃ , = . qrxn 1 2 99kJ ° , = , ∆H rxn 1 qrxn 1molMg ° , = . . × . ∆H rxn 1 2 99kJ0 1639gMg 24 31gMg1molMg ° , =- / ∆H rxn 1 443kJ mol , = qrxn 2 mc∆T , = . . - . qrxn 2 100g4 18Jg℃24 76℃ 20 93℃
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## This lab report was uploaded on 04/07/2008 for the course CHEM 1200 taught by Professor Mcintosh during the Spring '08 term at Rensselaer Polytechnic Institute.

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#1 Hess's Law - Aaron King 660556233 Section 1 February 6...

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