Set 8- Chapter 8 Using Table 8.4, estimate AH for the following reactions and indicate whether they are exothermic or endothermic a. H-N-N-H(g) | | HH NEN(g) + 2 H-H(g)
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.
![### Problem Set 8 - Chapter 8
**1. Using Table 8.4, estimate ΔH for the following reactions and indicate whether they are exothermic or endothermic.**
#### a.
\[ \text{H} - \text{N} \equiv \text{N} - \text{H}(g) \rightarrow \text{N} \equiv \text{N}(g) + 2 \text{H} - \text{H}(g) \]
**Explanation:**
The image presents a chemical equation involving the conversion of hydrazine (\( \text{H}_2\text{N}-\text{NH}_2 \)) in the gaseous phase to diatomic nitrogen (\( \text{N}_2 \)) and hydrogen gas (\( \text{H}_2 \)). The task is to estimate the change in enthalpy (\( \Delta H \)) for this reaction using bond enthalpy values from Table 8.4 and classify the reaction as exothermic or endothermic based on the calculated enthalpy change.
- **Reactants:**
- Hydrazine in gas form.
- **Products:**
- Nitrogen gas (\( \text{N}_2 \)) and hydrogen gas (\( \text{H}_2 \)).
**Diagrams/Equations:**
The equation highlights the breaking of N-H and N-N bonds in hydrazine to form new bonds in \( \text{N}_2 \) and \( \text{H}_2 \).
Students are expected to calculate the bond enthalpy for breaking and forming the chemical bonds and use these values to determine \( \Delta H \). Based on the sign of \( \Delta H \), they will classify the reaction as exothermic (releases heat) or endothermic (absorbs heat).](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff9cfd204-82c9-4d08-afab-e37570867926%2Fad1df1ad-d7da-4a62-bb13-62288f4d1ff8%2Fx0bjmfj_processed.jpeg&w=3840&q=75)
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