To determine which reaction is endothermic, we need to evaluate the total energy of bonds broken and the total energy of bonds formed for each reaction.
An endothermic reaction absorbs energy, meaning that the energy required to break the bonds is greater than the energy released when new bonds are formed.
Let's analyze each reaction:
-
C + O2 → CO2
- Bonds broken: O=O (499 kJ/mol)
- Bonds formed: 2 C=O (2 × 799 kJ/mol = 1598 kJ/mol)
- Total energy of bonds broken = 499 kJ/mol
- Total energy of bonds formed = 1598 kJ/mol
- Net energy change = 499 - 1598 = -1099 kJ/mol (exothermic)
-
N2 + O2 → 2NO
- Bonds broken: N≡N (946 kJ/mol) + O=O (499 kJ/mol) = 1445 kJ/mol
- Bonds formed: 2 N=O (2 × 946 kJ/mol = 1892 kJ/mol)
- Total energy of bonds broken = 1445 kJ/mol
- Total energy of bonds formed = 1892 kJ/mol
- Net energy change = 1445 - 1892 = -447 kJ/mol (exothermic)
-
S + O2 → SO2
- Bonds broken: O=O (499 kJ/mol)
- Bonds formed: 2 S=O (2 × 522 kJ/mol = 1044 kJ/mol)
- Total energy of bonds broken = 499 kJ/mol
- Total energy of bonds formed = 1044 kJ/mol
- Net energy change = 499 - 1044 = -545 kJ/mol (exothermic)
-
2CO + O2 → 2CO2
- Bonds broken: 2 C≡O (2 × 1072 kJ/mol = 2144 kJ/mol) + O=O (499 kJ/mol) = 2643 kJ/mol
- Bonds formed: 4 C=O (4 × 799 kJ/mol = 3196 kJ/mol)
- Total energy of bonds broken = 2643 kJ/mol
- Total energy of bonds formed = 3196 kJ/mol
- Net energy change = 2643 - 3196 = -553 kJ/mol (exothermic)
All of these reactions release energy, which means they are exothermic. If we are looking for an endothermic reaction, it would not be any of these options based on the given data.
However, since you are asking explicitly for which reaction is endothermic from the provided choices, none of the listed reactions appears to be endothermic according to the bond energies provided. Please ensure that the data or options are correct or consider that an endothermic reaction may not be included in this selection.