7. a) Hess's Law. Calculate AHxn° using Hess's Law. Fe₂O3(s) + 2Al(s) 2Al(s) + 3/202(g) 2Fe(s) + 3/2O2(g) - Al₂O3(s) + 2Fe(s) Al₂O3(s) Fe₂O3(s) Hran °= ? KJ Hrxn=-1676 kJ Hrxn=-824 kJ
7. a) Hess's Law. Calculate AHxn° using Hess's Law. Fe₂O3(s) + 2Al(s) 2Al(s) + 3/202(g) 2Fe(s) + 3/2O2(g) - Al₂O3(s) + 2Fe(s) Al₂O3(s) Fe₂O3(s) Hran °= ? KJ Hrxn=-1676 kJ Hrxn=-824 kJ
Chemistry
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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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![**7. a) Hess's Law.** Calculate ΔH°ₓₙ using Hess's Law.
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**Equation 1:**
\[ \text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow \text{Al}_2\text{O}_3(s) + 2\text{Fe}(s) \]
\[ \Delta H°ₓₙ = \,?\, \text{kJ} \]
---
**Equation 2:**
\[ 2\text{Al}(s) + \frac{3}{2}\text{O}_2(g) \rightarrow \text{Al}_2\text{O}_3(s) \]
\[ \Delta H°ₓₙ = -1676 \, \text{kJ} \]
---
**Equation 3:**
\[ 2\text{Fe}(s) + \frac{3}{2}\text{O}_2(g) \rightarrow \text{Fe}_2\text{O}_3(s) \]
\[ \Delta H°ₓₙ = -824 \, \text{kJ} \]
---
**b) Exothermic or endothermic?**
**Explanation:**
The diagram outlines three chemical equations. The first equation is the overall reaction for which the enthalpy change (ΔH°ₓₙ) needs to be calculated. The second and third equations are the steps with known enthalpy changes. According to Hess's Law, the enthalpy change of the overall reaction can be determined by manipulating the known equation steps. It involves reversing or scaling the steps to match the overall equation and summing their enthalpy changes. The exothermic or endothermic nature of the reaction can be determined once ΔH°ₓₙ is calculated.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5dbedc34-c1dd-4e16-ba9c-319b01d1eecb%2F44edde4a-658e-428e-9840-5cfe97f3964c%2Fbmgzt8b_processed.jpeg&w=3840&q=75)
Transcribed Image Text:**7. a) Hess's Law.** Calculate ΔH°ₓₙ using Hess's Law.
---
**Equation 1:**
\[ \text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow \text{Al}_2\text{O}_3(s) + 2\text{Fe}(s) \]
\[ \Delta H°ₓₙ = \,?\, \text{kJ} \]
---
**Equation 2:**
\[ 2\text{Al}(s) + \frac{3}{2}\text{O}_2(g) \rightarrow \text{Al}_2\text{O}_3(s) \]
\[ \Delta H°ₓₙ = -1676 \, \text{kJ} \]
---
**Equation 3:**
\[ 2\text{Fe}(s) + \frac{3}{2}\text{O}_2(g) \rightarrow \text{Fe}_2\text{O}_3(s) \]
\[ \Delta H°ₓₙ = -824 \, \text{kJ} \]
---
**b) Exothermic or endothermic?**
**Explanation:**
The diagram outlines three chemical equations. The first equation is the overall reaction for which the enthalpy change (ΔH°ₓₙ) needs to be calculated. The second and third equations are the steps with known enthalpy changes. According to Hess's Law, the enthalpy change of the overall reaction can be determined by manipulating the known equation steps. It involves reversing or scaling the steps to match the overall equation and summing their enthalpy changes. The exothermic or endothermic nature of the reaction can be determined once ΔH°ₓₙ is calculated.
Expert Solution
Step 1
Hess's Law: It states that for multiple steps of a reaction, the total enthalpy change for the reaction is the sum of all changes. This law describes that the enthalpy is a state function.
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