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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![Title: Calculating ΔG° for a Chemical Reaction
---
**Find ΔG° for the following reaction, using ΔH°f and S° values.**
\[ \text{H}_2(\text{g}) + \text{I}_2(\text{s}) \rightarrow 2 \text{HI}(\text{g}) \]
\[ \boxed{\ \ \ \ \ } \text{kJ} \]
---
### Explanation:
To calculate the standard Gibbs free energy change (ΔG°) for a chemical reaction, you will need to use standard enthalpy of formation (ΔH°f) and standard entropy (S°) values. The relationship between these thermodynamic quantities is given by the Gibbs free energy equation:
\[ ΔG° = ΔH° - TΔS° \]
Where:
- **ΔG°**: Standard Gibbs free energy change.
- **ΔH°**: Standard enthalpy change.
- **T**: Absolute temperature in Kelvin.
- **ΔS°**: Standard entropy change.
**Step-by-Step Process:**
1. **Determine the ΔH°f and S° values**: Look up the standard enthalpy of formation and the standard entropy for all reactants and products in a standard reference table.
2. **Calculate ΔH°**: Use the enthalpy values to find the enthalpy change of the reaction.
\[ ΔH° = Σ ΔH°f \text{(products)} - Σ ΔH°f \text{(reactants)} \]
3. **Calculate ΔS°**: Use the entropy values to find the entropy change of the reaction.
\[ ΔS° = Σ S° \text{(products)} - Σ S° \text{(reactants)} \]
4. **Insert values into the Gibbs free energy equation** to find ΔG°.
---
### Notes:
- Make sure to convert temperature to Kelvin (K): \( T (K) = T (°C) + 273.15 \).
- Ensure consistency in units when performing calculations, particularly for energy (Joules or kilojoules) and entropy (J/K).
### Example Problem:
Given hypothetical values for this reaction:
- \( ΔH°f[\text{H}_2(\text{g})] = 0 \ \text{kJ/mol} \)
- \( ΔH°](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe0ae19d5-3750-41df-884f-8ca3aa31e002%2F9d03b260-528d-4e3c-9d33-f4f89c4bb5d9%2Fymfetvj_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Title: Calculating ΔG° for a Chemical Reaction
---
**Find ΔG° for the following reaction, using ΔH°f and S° values.**
\[ \text{H}_2(\text{g}) + \text{I}_2(\text{s}) \rightarrow 2 \text{HI}(\text{g}) \]
\[ \boxed{\ \ \ \ \ } \text{kJ} \]
---
### Explanation:
To calculate the standard Gibbs free energy change (ΔG°) for a chemical reaction, you will need to use standard enthalpy of formation (ΔH°f) and standard entropy (S°) values. The relationship between these thermodynamic quantities is given by the Gibbs free energy equation:
\[ ΔG° = ΔH° - TΔS° \]
Where:
- **ΔG°**: Standard Gibbs free energy change.
- **ΔH°**: Standard enthalpy change.
- **T**: Absolute temperature in Kelvin.
- **ΔS°**: Standard entropy change.
**Step-by-Step Process:**
1. **Determine the ΔH°f and S° values**: Look up the standard enthalpy of formation and the standard entropy for all reactants and products in a standard reference table.
2. **Calculate ΔH°**: Use the enthalpy values to find the enthalpy change of the reaction.
\[ ΔH° = Σ ΔH°f \text{(products)} - Σ ΔH°f \text{(reactants)} \]
3. **Calculate ΔS°**: Use the entropy values to find the entropy change of the reaction.
\[ ΔS° = Σ S° \text{(products)} - Σ S° \text{(reactants)} \]
4. **Insert values into the Gibbs free energy equation** to find ΔG°.
---
### Notes:
- Make sure to convert temperature to Kelvin (K): \( T (K) = T (°C) + 273.15 \).
- Ensure consistency in units when performing calculations, particularly for energy (Joules or kilojoules) and entropy (J/K).
### Example Problem:
Given hypothetical values for this reaction:
- \( ΔH°f[\text{H}_2(\text{g})] = 0 \ \text{kJ/mol} \)
- \( ΔH°
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