2C (s) + 2H2 (g) → C2H4 (g) : ΔH = + 52.4 kJ/mol

Which statement about this reaction is correct?

Answer;

26.2 kJ of energy are absorbed for every mole of carbon reacted

Explanation; ΔH is the enthalpy change which is given by subtracting the energy of reactants from the energy of products. That is; ΔH = energy of products - energy of reactants In this case, it means that C2H4 has more energy than the the reactants. 52.4 J of energy to be precise, this energy is absorbed during the reaction. However, Two moles of Carbon require that much energy, thus one mole will require only 26.2 to react.