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Use the table to answer the question.%0D%0A%0D%0AReaction%09Bonds Present%09Energy of Bonds Broken and Formed (kJ/mol)%0D%0AC + O2→CO2 %09%0D%0AO=O %0D%0A%0D%0A2 C=O %0D%0A%0D%0A499 %0D%0A%0D%0A1478 %0D%0A%0D%0AN2+O2→2NO %09%0D%0AN≡N %0D%0A%0D%0AO=O %0D%0A%0D%0A2 N=O %0D%0A%0D%0A946 %0D%0A%0D%0A499 %0D%0A%0D%0A1214 %0D%0A%0D%0AS+O2→SO2 %09%0D%0AO=O %0D%0A%0D%0A2 S=O %0D%0A%0D%0A499 %0D%0A%0D%0A1044 %0D%0A%0D%0A2CO+O2→2CO2 %09%0D%0A2 C≡O %0D%0A%0D%0AO=O %0D%0A%0D%0A4 C=O %0D%0A%0D%0A2148 %0D%0A%0D%0A499 %0D%0A%0D%0A2956 %0D%0A%0D%0AWhich reaction is endothermic?%0D%0A%0D%0A(1 point)%0D%0AResponses%0D%0A%0D%0A2CO+O2→2CO2%0D%0A2 C O plus O sub 2 rightarrow 2 C O sub 2%0D%0A%0D%0AS+O2→SO2%0D%0AS plus O sub 2 rightarrow S O sub 2%0D%0A%0D%0AN2+O2→2NO%0D%0AN sub 2 plus O sub 2 rightarrow 2 N O%0D%0A%0D%0AC + O2→CO2

1 answer

To determine which reaction is endothermic, we need to compare the total energy required to break the bonds in the reactants with the total energy released by forming the bonds in the products. If breaking bonds requires more energy than is released by forming bonds, the reaction is endothermic.

Let's analyze each reaction using the provided bond energies:

  1. C + O₂ → CO₂

    • Bonds broken: 1 O=O (499 kJ/mol)
    • Bonds formed: 2 C=O (1478 kJ/mol total)
    • Net energy change = Energy of bonds broken - Energy of bonds formed = 499 - 1478 = -979 kJ (exothermic)

  2. N₂ + O₂ → 2NO

    • Bonds broken: 1 N≡N (946 kJ/mol) + 1 O=O (499 kJ/mol) = 1445 kJ
    • Bonds formed: 2 N=O (1214 kJ/mol total)
    • Net energy change = 1445 - 1214 = 231 kJ (endothermic)

  3. S + O₂ → SO₂

    • Bonds broken: 1 O=O (499 kJ/mol)
    • Bonds formed: 2 S=O (1044 kJ/mol total)
    • Net energy change = 499 - 1044 = -545 kJ (exothermic)

  4. 2CO + O₂ → 2CO₂

    • Bonds broken: 2 C≡O (2148 kJ/mol) + 1 O=O (499 kJ/mol) = 2647 kJ
    • Bonds formed: 4 C=O (2956 kJ/mol total)
    • Net energy change = 2647 - 2956 = -309 kJ (exothermic)

From the analysis above:

  • The only endothermic reaction from the provided reactions is N₂ + O₂ → 2NO.

Answer: N₂ + O₂ → 2NO