Final answer:
Enthalpy change (ΔH) for a reaction is calculated by subtracting the energy released in bond formation from the energy used in bond breaking. In the given example, the reaction of H₂ and Cl₂ to form HCl releases 185 kJ of energy, indicating an exothermic reaction.
Step-by-step explanation:
To calculate the enthalpy change (ΔH) for the reaction CO(g) + Cl₂(g) → Cl₂CO(g), we need to consider the bond energies involved in breaking and forming chemical bonds during the reaction. Breaking bonds consumes energy, while forming new bonds releases energy.
The general formula for calculating the enthalpy of reaction using bond energies is: ΔH = Energy used in bond breaking - Energy released in bond formation.
Since the exact bond energies for the reactants and products are not provided in the question, we would follow these steps to solve a similar problem:
- Identify the bonds broken in the reactants and calculate the total energy required to break them.
- Identify the bonds formed in the products and calculate the total energy released during their formation.
- Subtract the energy released from the energy used to find the ΔH for the reaction.
For the provided example of H₂ and Cl₂ reacting to form HCl, the enthalpy change is calculated as follows:
Bond energies for bond breaking:
H-H bond = 436 kJ/mol,
Cl-Cl bond = 243 kJ/mol.
Total energy required = 436 kJ + 243 kJ = 679 kJ.
Bond energies for bond formation:
2 H-Cl bonds = 2 × 432 kJ/mol = 864 kJ.
Total energy released = 864 kJ.
The enthalpy of reaction (ΔH):
679 kJ - 864 kJ = -185 kJ.
Note: The negative sign indicates that the reaction is exothermic, releasing heat to the surroundings.