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Heat evolved in the reaction H(2)+Cl(2...

Heat evolved in the reaction
`H_(2)+Cl_(2) rarr 2HCl` is 182 kJ Bond energies H- H = 430 kJ/mole, `Cl-Cl = 242kJ//"mole"`. The H-Cl bond energy is

A

763 kJ/mole

B

427 kJ/mole

C

336 kJ/mole

D

154 kJ/mole

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The correct Answer is:
To find the bond energy of H-Cl in the reaction \( H_2 + Cl_2 \rightarrow 2HCl \), we can use the concept of bond energies and the heat evolved in the reaction. ### Step-by-Step Solution: 1. **Identify the Given Data:** - Heat evolved in the reaction (\( \Delta H \)): -182 kJ (negative because heat is released) - Bond energy of \( H-H \): 430 kJ/mole - Bond energy of \( Cl-Cl \): 242 kJ/mole - Let the bond energy of \( H-Cl \) be \( x \) kJ/mole. 2. **Write the Reaction:** The reaction can be broken down into bonds broken and bonds formed: \[ H_2 + Cl_2 \rightarrow 2HCl \] 3. **Calculate the Total Energy of Bonds Broken:** - Bonds broken: 1 \( H-H \) bond and 1 \( Cl-Cl \) bond. - Total energy required to break these bonds: \[ \text{Energy of bonds broken} = \text{Bond energy of } H-H + \text{Bond energy of } Cl-Cl = 430 \, \text{kJ} + 242 \, \text{kJ} = 672 \, \text{kJ} \] 4. **Calculate the Total Energy of Bonds Formed:** - Bonds formed: 2 \( H-Cl \) bonds. - Total energy released when forming these bonds: \[ \text{Energy of bonds formed} = 2 \times x \, \text{kJ} \] 5. **Apply Hess's Law:** According to Hess's law, the heat evolved in the reaction can be expressed as: \[ \Delta H = \text{Energy of bonds broken} - \text{Energy of bonds formed} \] Substituting the values: \[ -182 \, \text{kJ} = 672 \, \text{kJ} - 2x \] 6. **Rearranging the Equation:** Rearranging the equation to solve for \( x \): \[ 2x = 672 \, \text{kJ} + 182 \, \text{kJ} \] \[ 2x = 854 \, \text{kJ} \] \[ x = \frac{854}{2} \, \text{kJ} = 427 \, \text{kJ/mole} \] 7. **Conclusion:** The bond energy of \( H-Cl \) is \( 427 \, \text{kJ/mole} \).

To find the bond energy of H-Cl in the reaction \( H_2 + Cl_2 \rightarrow 2HCl \), we can use the concept of bond energies and the heat evolved in the reaction. ### Step-by-Step Solution: 1. **Identify the Given Data:** - Heat evolved in the reaction (\( \Delta H \)): -182 kJ (negative because heat is released) - Bond energy of \( H-H \): 430 kJ/mole - Bond energy of \( Cl-Cl \): 242 kJ/mole ...
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