### Understanding Standard Heat of Formation and Reaction The concept of standard heat of formation, denoted as \(\Delta H_f^\circ\), is essential in chemistry. It is defined as the enthalpy change required to form one mole of a substance from its constituent elements in their standard states. Elements in their standard states have \(\Delta H_f^\circ = 0\). These values are crucial as they enable the calculation of the enthalpy change of any reaction.**Example Reaction:**\[ 2NO(g) + O_2(g) \rightarrow 2NO_2(g) \]Using the following heat of formation values:| Substance | \(\Delta H_f^\circ\) (kJ/mol) ||-----------|-------------------------------|| NO(g) | 90.2 || O\(_2\)(g)| 0.0 || NO\(_2\)(g)| 33.2 |The standard heat of reaction for the overall reaction can be calculated as:\[\Delta H_{rxn}^\circ = \sum \Delta H_f^\circ (\text{products}) - \sum \Delta H_f^\circ (\text{reactants})\]\[= [2(33.2)] - [2(90.2) + 0]\]\[= 66.4 - 180.4\]\[= -114 \text{ kJ}\]**Part B:**The combustion of heptane, \( C_7H_{16} \), occurs via the reaction:\[ C_7H_{16}(g) + 11O_2(g) \rightarrow 7CO_2(g) + 8H_2O(g) \]Using the heat of formation values from the table:| Substance | \(\Delta H_f^\circ\) (kJ/mol) ||-----------|-------------------------------|| \( C_7H_{16}(g) \) | -187.9 || \( CO_2(g) \) | -393.5 || \( H_2O(g) \) | -241.8 |Calculate the enthalpy for the combustion of 1 mole of heptane. Express your answer to four significant figures and include the appropriate units.\[\Delta H_{rxn}

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Keview | Constants | Perodic Tabl Part B The combustion of heptane, C7H16, occurs via the reaction C;H16(g) + 1102(g)→7CO2(g) + 8H,0(g) with heat of formation values given by the following table: AH (kJ/mol) Substance C,H16 (g) -187.9 CO2(g) -393.5 H2O(g) -241.8 Calculate the enthalpy for the combustion of 1 mole of heptane. Express your answer to four significant figures and include the appropriate units. • View Available Hint(s) HA AHa = Value Units Submit Previous Answers X Incorrect; Try Again; 3 attempts remaining Standard heat of formation values are given in kJ/mol. however when calculating the enthalpy of combustion for a specific reaction you must multiply each formation value by the coefficient in the chemical equation. This coefficient represent the number of moles of each compound, thus the final units should be in kJ. You mav want to review Hint 1. How to anoroach the nemblem P Pearson Huration Inc. All rights reserved. I Terms of Use | Privacy Policy | Permissions I Contact Us

Keview | Constants | Perodic Tabl Part B The combustion of heptane, C7H16, occurs via the reaction C;H16(g) + 1102(g)→7CO2(g) + 8H,0(g) with heat of formation values given by the following table: AH (kJ/mol) Substance C,H16 (g) -187.9 CO2(g) -393.5 H2O(g) -241.8 Calculate the enthalpy for the combustion of 1 mole of heptane. Express your answer to four significant figures and include the appropriate units. • View Available Hint(s) HA AHa = Value Units Submit Previous Answers X Incorrect; Try Again; 3 attempts remaining Standard heat of formation values are given in kJ/mol. however when calculating the enthalpy of combustion for a specific reaction you must multiply each formation value by the coefficient in the chemical equation. This coefficient represent the number of moles of each compound, thus the final units should be in kJ. You mav want to review Hint 1. How to anoroach the nemblem P Pearson Huration Inc. All rights reserved. I Terms of Use | Privacy Policy | Permissions I Contact Us

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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Ff.130.
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