3. Compounds with a carbon - carbon double bond (such as ethene) add hydrogen in a reaction called hydrogenation.C2H4(g) + H2(g) C2H6(g)Calculate the enthalpy change for this reaction using the following combustion data:C2H4(g) + 302(g) 2CO2(g) + 2H2O(l); H = -1411 kJC2H6(g) + 7/2 O2(g) 2CO2(g) + 3H2O(l); H = -1560 kJH2(g) + (1)/(2) O2(g) H2O(l); H = -286kJ
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.
![**Topic: Hydrogenation and Enthalpy Change Calculation**
**Question 3:**
Compounds with a carbon-carbon double bond, such as ethene, add hydrogen in a reaction called hydrogenation. The balanced chemical equation for this reaction is:
\[ \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{(g)} \rightarrow \text{C}_2\text{H}_6\text{(g)} \]
**Objective:**
Calculate the enthalpy change for this reaction using the given combustion data.
**Combustion Data:**
1. \(\text{C}_2\text{H}_4\text{(g)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} + 2\text{H}_2\text{O(l)}; \quad \Delta H = -1411 \, \text{kJ}\)
2. \(\text{C}_2\text{H}_6\text{(g)} + \frac{7}{2} \text{O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} + 3\text{H}_2\text{O(l)}; \quad \Delta H = -1560 \, \text{kJ}\)
3. \(\text{H}_2\text{(g)} + \frac{1}{2} \text{O}_2\text{(g)} \rightarrow \text{H}_2\text{O(l)}; \quad \Delta H = -286 \, \text{kJ}\)
**Enthalpy Change Calculation:**
The enthalpy change for the hydrogenation reaction is calculated using Hess's Law, based on the given combustion reactions. By manipulating and combining these equations, the enthalpy change for the desired reaction is derived.
**Result:**
\[ \Delta H = -286 \, \text{kJ} \]
This provides the enthalpy change for the hydrogenation of ethene to form ethane.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe0fc17c9-9425-45af-ac3e-e3d09bfdb08a%2F2b6ce86e-6e02-48cb-ae43-fca27cb6bf12%2Fg3suadm_processed.png&w=3840&q=75)
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