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VLD [36.1K]
3 years ago
7

Acetylene gas (ethyne; HC≡CH) burns with oxygen in an oxyacetylene torch to produce carbon dioxide, water vapor, and the heat ne

eded to weld metals. The heat of combustion for acetylene is −1259 kJ/mol. Calculate the C≡C bond energy._________ kJ/mol.
Chemistry
1 answer:
makkiz [27]3 years ago
4 0

Answer : The bond energy of C\equiv C is 800 kJ/mol.

Explanation :

The given chemical reaction is:

2C_2H_2+5O_2\rightarrow 4CO_2+2H_2O

For 1 mole, the reaction will be:

C_2H_2+2.5O_2\rightarrow 2CO_2+H_2O

As we know that:

The enthalpy change of reaction = E(bonds broken) - E(bonds formed)

\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})]

Given:

\Delta H = heat of combustion = -1259 kJ/mol

B.E_{C-H} = 413 kJ/mol

B.E_{O=O} = 498 kJ/mol

B.E_{O-H} = 467 kJ/mol

B.E_{C=O} = 799 kJ/mol

Now put all the given values in the above expression, we get:

-1259kJ/mol=[(B.E_{C\equiv C})+(2\times 413kJ/mol)+(2.5\times 498kJ/mol)]-[(4\times 799kJ/mol)+(2\times 467kJ/mol)]

B.E_{C\equiv C}=800kJ/mol

Therefore, the bond energy of C\equiv C is 800 kJ/mol.

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