Respuesta :
Answer : The bond energy of [tex]C\equiv C[/tex] is 800 kJ/mol.
Explanation :
The given chemical reaction is:
[tex]2C_2H_2+5O_2\rightarrow 4CO_2+2H_2O[/tex]
For 1 mole, the reaction will be:
[tex]C_2H_2+2.5O_2\rightarrow 2CO_2+H_2O[/tex]
As we know that:
The enthalpy change of reaction = E(bonds broken) - E(bonds formed)
[tex]\Delta H=[(B.E_{C\equiv C})+(2\times B.E_{C-H})+(2.5\times B.E_{O=O})]-[(2\times B.E_{C=O})+(2\times B.E_{H-O})][/tex]
Given:
[tex]\Delta H[/tex] = heat of combustion = -1259 kJ/mol
[tex]B.E_{C-H}[/tex] = 413 kJ/mol
[tex]B.E_{O=O}[/tex] = 498 kJ/mol
[tex]B.E_{O-H}[/tex] = 467 kJ/mol
[tex]B.E_{C=O}[/tex] = 799 kJ/mol
Now put all the given values in the above expression, we get:
[tex]-1259kJ/mol=[(B.E_{C\equiv C})+(2\times 413kJ/mol)+(2.5\times 498kJ/mol)]-[(4\times 799kJ/mol)+(2\times 467kJ/mol)][/tex]
[tex]B.E_{C\equiv C}=800kJ/mol[/tex]
Therefore, the bond energy of [tex]C\equiv C[/tex] is 800 kJ/mol.
