The standard enthalpy of formation of CO2 is -393.5 kJ/mol. What is the standard enthalpy of formation of carbon (C) if the standard enthalpy of combustion of carbon is -393.5 kJ/mol?
Correct: A
The standard enthalpy of formation of an element in its standard state is defined as zero. Since carbon (C) is an element, its standard enthalpy of formation is 0 kJ/mol.