Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![**Given:**
\[ \text{C}_2\text{H}_4(g) + 3\text{O}_2(g) \rightarrow 2\text{CO}_2(g) + 2\text{H}_2\text{O}(g) \]
\[ \Delta H_f(\text{C}_2\text{H}_4) = 52.5 \, \text{kJ/mol} \]
\[ \Delta H_f(\text{H}_2\text{O}) = -285.8 \, \text{kJ/mol} \]
\[ \Delta H^\circ_{\text{rxn}} = -1411.1 \, \text{kJ/mol} \]
**Find \(\Delta H_f(\text{CO}_2)\):**
- View Available Hint(s):
- \(-1358 \, \text{kJ/mol}\)
- \(+393.5 \, \text{kJ/mol}\)
- \(-1303.5 \, \text{kJ/mol}\)
- \(-393.5 \, \text{kJ/mol}\)
**[Submit]**](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbb31c72c-4045-4dee-afe2-8fb7977f2141%2Feecaa0a3-9a30-408d-ac9d-7839947b3181%2Fz6h603i_processed.jpeg&w=3840&q=75)
![**Thermochemistry Calculation: Determining ΔH for a Reaction**
Calculate the enthalpy change (ΔH) for the following reaction:
\[ \text{C(s) + H}_2\text{O(g)} \rightarrow \text{CO(g) + H}_2\text{(g)} \]
**Given Thermochemical Equations:**
1. \( \text{C(s) + O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} \)
\( \Delta H_1 = -393.5 \, \text{kJ} \)
2. \( 2\text{CO(g) + O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} \)
\( \Delta H_2 = -566.0 \, \text{kJ} \)
3. \( 2\text{H}_2\text{(g) + O}_2\text{(g)} \rightarrow 2\text{H}_2\text{O(g)} \)
\( \Delta H_3 = -483.6 \, \text{kJ} \)
**Multiple Choice Answers:**
- 918.3 kJ
- 1443.1 kJ
- 262.6 kJ
- 131.3 kJ
- 656.1 kJ
**Instructions:**
To find the correct enthalpy change for the given reaction, use Hess's Law to combine the given thermochemical equations. Select the correct answer from the provided options.
Click "Submit" to confirm your answer.
**Note:** The calculations should involve manipulation of the given equations to derive the target reaction.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbb31c72c-4045-4dee-afe2-8fb7977f2141%2Feecaa0a3-9a30-408d-ac9d-7839947b3181%2Fymnxjze_processed.jpeg&w=3840&q=75)
Note: Since, multiple questions have been asked, therefore as per the guidelines, solution of 1st question has been made. For the expert solution of 2nd question kindly post it separately.
Answer:
Enthalpy of reaction is always equal to the difference between enthalpy of formation of product and reactants.
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