Chemistry · THERMODYNAMICS

Consider the following thermochemical reactions: (i) \( \text{C}(\text{graphite}) + \text{O}_2(g) \rightarrow \text{CO}_2(g) \); \( \Delta_r H^\ominus = -393.5\text{ kJ mol}^{-1} \) (ii) \( \text{CO}(g) + \frac{1}{2}\text{O}_2(g) \rightarrow \text{CO}_2(g) \); \( \Delta_r H^\ominus = -283.0\text{ kJ mol}^{-1} \) Applying Hess's law, the standard enthalpy of formation of \( \text{CO}(g) \) is:

1. A
   +110.5 kJ mol⁻¹
2. B
   -110.5 kJ mol⁻¹
3. C
   +676.5 kJ mol⁻¹
4. D
   -676.5 kJ mol⁻¹