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.
Use the molar bond enthalpy data in the table to estimate the value of Delta H°rxn for the equation:
CCI4(g) + 2 F2(g) = CF4(g) + 2 Cl2(g)
![**Bond Enthalpy Calculation for Reaction**
### Reaction Equation:
To estimate the value of the enthalpy change (\( \Delta H_{\text{rxn}} \)) for the reaction:
\[ \text{CCl}_4 (g) + 2 \text{F}_2 (g) \rightarrow \text{CF}_4 (g) + 2 \text{Cl}_2 (g) \]
### Molecular Structures:
- **CCl\(_4\):** A central carbon atom bonded to four chlorine atoms.
- **F\(_2\):** Two fluorine atoms bonded together.
- **CF\(_4\):** A central carbon atom bonded to four fluorine atoms.
- **Cl\(_2\):** Two chlorine atoms bonded together.
### Table of Average Molar Bond Enthalpies (\(H_{\text{bond}}\)):
| **Bond** | **kJ·mol\(^{-1}\)** | **Bond** | **kJ·mol\(^{-1}\)** |
|----------|---------------------|----------|---------------------|
| O–H | 464 | C≡N | 890 |
| O–O | 142 | N–H | 390 |
| C–O | 351 | N–N | 159 |
| O=O | 502 | N=N | 418 |
| C=O | 730 | N≡N | 945 |
| C–C | 347 | F–F | 155 |
| C=C | 615 | Cl–Cl | 243 |
| C≡C | 811 | Br–Br | 192 |
| C–H | 414 | H–H | 435 |
| C–F | 439 | H–F | 565 |
| C–Cl | 331 | H–Cl | 431 |
| C–Br | 276 | H–Br | 368 |
| C–N | 293 | H–S | 364 |
### Explanation for Educational Purpose:
This setup allows students to calculate the reaction enthalpy by considering the bonds broken and formed during the chemical](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9119b5ec-4182-4648-90e9-9bd76e84844a%2Fc9af9f2c-43a2-4622-be17-2907b624f9f6%2Fvtnz1sd_processed.png&w=3840&q=75)
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