Concept:The standard enthalpy of formation is the heat change when one mole of a compound is synthesized from its constituent elements in their standard physical states under standard conditions (298 K, 1 atm).
Formula:$$ C_{(s, \text{graphite})} + O_{2(g)} \rightarrow CO_{2(g)} $$
Solution:- The formation of carbon dioxide from solid graphite and gaseous oxygen is highly exothermic because it creates very stable covalent double bonds.
- The experimentally determined value for this complete oxidation (which is also the enthalpy of combustion of graphite) releases exactly \( -394 \text{ kJ/mol} \).
Why other options are incorrect:Option B is positive (endothermic), which is impossible for this combustion process. Options A and C are incorrect numerical values.
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