Estimate the enthalpy change for the reaction 2CO + O₂ $\rarr$ 2CO₂ given the following bond energies.
BE(C $\equiv$ O) = 1074 kJ/mol
BE(O=O) = 499 kJ/mol
BE(C=O) = 802 kJ/mol

Question

Estimate the enthalpy change for the reaction 2CO + O₂

\rarr

2CO₂ given the following bond energies.
BE(C

\equiv

O) = 1074 kJ/mol
BE(O=O) = 499 kJ/mol
BE(C=O) = 802 kJ/mol

Quizplus · Accepted Answer

The enthalpy change for the reaction can be calculated using the bond energy equation:

ΔH = ΣBE(bonds broken) - ΣBE(bonds formed)

We need to break the bonds in CO, O2, and F2 and form the bonds in CO and COS. Taking into account the coefficients of the balanced chemical equation, we have:

ΔH = 2(1/2 BE(O2) + BE(CO) + 3/2 BE(F2)) - 2 BE(CO) - BE(COS)
    = 2(1/2*499 + 802 + 3/2*2*435) - 2*1074 - 628
    = -561 kJ/mol

Therefore, the answer is D, -561 kJ/mol, which is the only negative value among the answer choices. This indicates that the reaction is exothermic, and that energy is released.

Estimate the Enthalpy Change for the Reaction 2CO + O2 →\rarr→

Estimate the Enthalpy Change for the Reaction 2CO + O₂ $\rarr$