The enthalpy of combustion and the standard enthalpy of formation of a fuel can be determined by measuring the temperature change in a calorimeter when a weighed amount of the fuel is burned in oxygen. (a) Write a balanced chemical equation for the combus- tion of isooctane, C3H18(€), to CO2(g) and H2O(€). Isooctane is a component of gasoline and is used as a reference standard in determining the “octane rating" of a fuel mixture. (b) Suppose 0.542 g isooctane is placed in a fixed-volume (bomb) calorimeter, which contains 750 g water, ini- tially at 20.450°C, surrounding the reaction compart- ment. The heat capacity of the calorimeter itself (excluding the water) has been measured to be 48 J K-1 in a separate calibration. After the combustion of the isooctane is complete, the water temperature is mea- sured to be 28.670°C. Taking the specific he: to be 4.184 J K-1g¬!, calculate AU for the combustion of 0.542 g isooctane. (c) Calculate AU for the combustion of 1 mol isooctane. (d) Calculate AH for the combustion of 1 mol isooctane. (e) Calculate AH°; for the isooctane.

The enthalpy of combustion and the standard enthalpy of formation of a fuel can be determined by measuring the temperature change in a calorimeter when a weighed amount of the fuel is burned in oxygen. (a) Write a balanced chemical equation for the combus- tion of isooctane, C3H18(€), to CO2(g) and H2O(€). Isooctane is a component of gasoline and is used as a reference standard in determining the “octane rating" of a fuel mixture. (b) Suppose 0.542 g isooctane is placed in a fixed-volume (bomb) calorimeter, which contains 750 g water, ini- tially at 20.450°C, surrounding the reaction compart- ment. The heat capacity of the calorimeter itself (excluding the water) has been measured to be 48 J K-1 in a separate calibration. After the combustion of the isooctane is complete, the water temperature is mea- sured to be 28.670°C. Taking the specific he: to be 4.184 J K-1g¬!, calculate AU for the combustion of 0.542 g isooctane. (c) Calculate AU for the combustion of 1 mol isooctane. (d) Calculate AH for the combustion of 1 mol isooctane. (e) Calculate AH°; for the isooctane.

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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