tión enthalpies Consider the following unbalanced reaction: ? Al(s) +? Fe203 (s) ===> Al,03 (s) + 2 Fe(s), AHrxn=? Thermodynamic data at 298.15 K: AHf(Fe203) = -822.16 kļ/mol, AHf(Al203) = -1669.8 k/mol. %3D The specific heat capacity of copper (Cu)-0.376812 g K), assumed to be constant. The molar mass of aluminum and Al203 is 26.98153849 and 101.961276 g/mol, respectively. (1) Calculate AHrxn from the formation enthalpies. Is the rn exothermic or endothermic? Solution: -847.64 kJ. Exothermic. AHrxn = (-1669.8)-(-822.16)=-847.64 kJ per 2 mol of Al (2) Calculate the reaction enthalpy per gram of Al(s). Solution: -15.71 k/ gram of AI. (-(847.64 / 2) kJ/mol of Al)/ (26.98 g/mol of Al)-. -15.71 k/gram of Al. (3) Assume that only 20 % of the released energy can be used to heat a metal (the 80 % remaining is wasted energy). How many grams of Al (s) are needed to heat a copper (Cu) mass of 1 kg by 100 Celsius? Solution: 12 g of Al(s).

tión enthalpies Consider the following unbalanced reaction: ? Al(s) +? Fe203 (s) ===> Al,03 (s) + 2 Fe(s), AHrxn=? Thermodynamic data at 298.15 K: AHf(Fe203) = -822.16 kļ/mol, AHf(Al203) = -1669.8 k/mol. %3D The specific heat capacity of copper (Cu)-0.376812 g K), assumed to be constant. The molar mass of aluminum and Al203 is 26.98153849 and 101.961276 g/mol, respectively. (1) Calculate AHrxn from the formation enthalpies. Is the rn exothermic or endothermic? Solution: -847.64 kJ. Exothermic. AHrxn = (-1669.8)-(-822.16)=-847.64 kJ per 2 mol of Al (2) Calculate the reaction enthalpy per gram of Al(s). Solution: -15.71 k/ gram of AI. (-(847.64 / 2) kJ/mol of Al)/ (26.98 g/mol of Al)-. -15.71 k/gram of Al. (3) Assume that only 20 % of the released energy can be used to heat a metal (the 80 % remaining is wasted energy). How many grams of Al (s) are needed to heat a copper (Cu) mass of 1 kg by 100 Celsius? Solution: 12 g of Al(s).

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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