For the following combustion reaction CH3CH₂CH₂COOH(1) +502(g) → 4CO₂(g) + 4H₂O(g) AH = -2.18 × 10³ kJ When a 7.52-g sample of butyric acid (molar mass = 88.10 g/mol) is burned, how much energy (in kJ) is released as heat?
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.
![**Combustion Reaction Analysis**
For the following combustion reaction:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{COOH}(l) + 5\text{O}_2(g) \rightarrow 4\text{CO}_2(g) + 4\text{H}_2\text{O}(g) \quad \Delta H = -2.18 \times 10^3 \, \text{kJ} \]
**Problem Statement:**
When a 7.52-g sample of butyric acid (molar mass = 88.10 g/mol) is burned, how much energy (in kJ) is released as heat?
**Analysis:**
- The chemical equation represents the combustion of butyric acid, releasing carbon dioxide and water.
- The enthalpy change (\( \Delta H \)) is negative, indicating an exothermic reaction where 2180 kJ of energy is released per mole of butyric acid burned.
- To calculate the energy released from burning 7.52 g of butyric acid, use the formula:
1. **Calculate Moles of Butyric Acid:**
\[
\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{7.52 \, \text{g}}{88.10 \, \text{g/mol}}
\]
2. **Calculate Energy Released:**
\[
\text{Energy (kJ)} = \text{moles} \times \Delta H
\]
This calculation will determine the amount of energy released when 7.52 g of butyric acid is combusted.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc42f8bf5-c4ea-440d-bf0d-c8a9270c2068%2F4dd4f1e2-bdb7-4076-8653-6e9ce019236f%2Fe9hx14_processed.jpeg&w=3840&q=75)
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