Question

Reaction

Bonds Present

Energy of Bonds Broken and Formed (kJ / m * ol)

C + O_{2} -> C*O_{2}

O = O

499

2C = 0

1478

N_{2} + O_{2} -> 2NO

N equiv N

946

O = 0

499

2N = 0

1214

S + O_{2} -> S*O_{2}

0=0

499

2S = O

1044

2CO + O_{2} -> 2C*O_{2}

2 C equiv0

2148

O = O

499

4C = 0

2956

Which reaction is endothermic?

(1 point)

N_{2} + O_{2} -> 2NO

C + O_{2} -> C*O_{2}

S + O_{2} -> S*O_{2}

2CO + O_{2} -> 2C*O_{2}

Answer 1

To determine which reaction is endothermic, we need to analyze the energy of bonds broken and formed in each reaction.

An endothermic reaction absorbs energy, meaning that the total energy of the bonds broken is greater than the total energy of the bonds formed.

Let's summarize the given reactions and their corresponding bond energies:

1. **\(N_{2} + O_{2} \rightarrow 2NO\)**
- Bonds broken: 946 kJ (N≡N) + 499 kJ (O=O) = 1445 kJ
- Bonds formed: 2(214 kJ) = 428 kJ
- Net energy: 1445 kJ (broken) - 428 kJ (formed) = 1017 kJ absorbed (endothermic)

2. **\(C + O_{2} \rightarrow CO_{2}\)**
- Bonds broken: 499 kJ (O=O) + 2(347 kJ) = 499 kJ + 694 kJ = 1193 kJ
- Bonds formed: 2(799 kJ) = 1598 kJ
- Net energy: 1193 kJ (broken) - 1598 kJ (formed) = -405 kJ (exothermic)

3. **\(S + O_{2} \rightarrow SO_{2}\)**
- Bonds broken: 0 kJ + 499 kJ (O=O) = 499 kJ
- Bonds formed: 2(499 kJ) = 998 kJ
- Net energy: 499 kJ (broken) - 998 kJ (formed) = -499 kJ (exothermic)

4. **\(2CO + O_{2} \rightarrow 2CO_{2}\)**
- Bonds broken: 2(1072 kJ) + 499 kJ = 2144 kJ + 499 kJ = 2643 kJ
- Bonds formed: 2(799 kJ) = 1598 kJ
- Net energy: 2643 kJ (broken) - 1598 kJ (formed) = 1045 kJ absorbed (endothermic)

Based on this analysis, both the **\(N_{2} + O_{2} \rightarrow 2NO\)** and **\(2CO + O_{2} \rightarrow 2CO_{2}\)** reactions are endothermic.

However, since you're asking for a single endothermic reaction, based on the choices given:

- **\(N_{2} + O_{2} \rightarrow 2NO\)** is endothermic.

Therefore, the answer is:

**\(N_{2} + O_{2} \rightarrow 2NO\)**