The enthalpy of formation for a substance corresponds to the enthalpy change for a reaction. Write the specific chemical reaction defining the enthalpy of formation of butane:
Just checking to make sure this is correct:
4C + 5H2 ---> C4H10
Looks ok to me.
Yes, you are correct! The enthalpy of formation of butane (C4H10) can be determined by the following balanced chemical equation:
2C(graphite) + 5H2(g) → C4H10(g)
In this reaction, 2 moles of carbon atoms in the form of graphite (C) combine with 5 moles of hydrogen gas (H2) to produce 1 mole of butane (C4H10). This balanced equation represents the formation of butane from its constituent elements in their standard states (where elements are in their most stable and common form at 25°C and 1 atm pressure).
The enthalpy change associated with this reaction is the enthalpy of formation of butane (∆Hf). Since the enthalpy of formation is defined as the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states, the enthalpy of formation of butane (∆Hf) can be determined by measuring the energy change during this reaction.