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chem_post_lab_6 - Mark Nowey Chem-09 Group 12 Amanda...

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Mark Nowey Chem -09 Group 12 Amanda Nicklin Post Lab #5 Thermochemistry 1. ΔT= T f – T i ΔT= (30.74ºC)-(26.86ºC) ΔT= 3.88ºC (endothermic) Cp Calorimeter = -q rxn –(mass of soln.)(Cp water ) (ΔT) ΔT Cp Calorimeter = (2.915kJ)(1000J/1kJ)-(100g )(4.18 J/g ºC)(3.88 ºC) (3.88 ºC) Cp Calorimeter = 333.4 J/gC 2. Ammonium Nitrate ΔT= T f – T i ΔT= (18.41 ºC- 25.04 ºC) ΔT= - 6.63 ºC ΔT= 6.63 ºC (endothermic) . 3. q salt =- [q water ] q salt = [50g x 4.18 E-3 J/g ºC x -6.63 ºC] q salt = 1.39 kJ kJ x g-1= (1.39kJ)/(5.012g) kJ x g-1= .28 kJ/g #moles = (sample mass)/(molar mass) #moles= (5.012g NH 4 NO 3 )/ (80g/mol NH 4 NO 3 ) #moles= .063 mol kJ x mol-1= (1.39 kJ/ .063) kJ x mol-1= 22.1 kJ x mol-1 Accepted 25.7 kJ/mole %error= (Measured-Accepted)/Accepted x100 %error= 14% 1. Potassium Nitrate ΔT= T f – T i ΔT= (17.89 ºC- 25.16 ºC) ΔT= - 7.27 ºC ΔT= 7.27 ºC (endothermic) . 2. q salt =- [q water ] q salt = [50g x 4.18 E-3 J/g ºC x -7.27 ºC] q salt = 1.52 kJ
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kJ x g-1= (1.52kJ)/(5.026g) kJ x g-1= .30 kJ/g #moles = (sample mass)/(molar mass) #moles= (5.026g NH 4 NO 3 )/ (80g/mol NH 4 NO 3 ) #moles= .063 mol kJ x mol-1= (1.52 kJ/ .063)
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