Calculate the amount of energy released when Methane is burned.
CH4 + 2O2 ==> CO2 + 2H2O
delta Hrxn = (n*sum deltaHf products) - (n*sum deltaHf reactants)
Look up delta Hf in tables in your text or notes.
To calculate the amount of energy released when methane (CH4) is burned, you can use the concept of enthalpy of combustion. The enthalpy of combustion (ΔHc) represents the amount of energy released when one mole of a substance is completely burned in oxygen.
The balanced equation for the combustion of methane is:
CH4 + 2O2 -> CO2 + 2H2O
The enthalpy change for this reaction can be determined from the standard enthalpy of formation (∆Hf) values for each substance involved. The standard enthalpy of formation is the enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states.
The standard enthalpy of formation values for methane (CH4), carbon dioxide (CO2), and water (H2O) are:
∆Hf(CH4) = -74.8 kJ/mol
∆Hf(CO2) = -393.5 kJ/mol
∆Hf(H2O) = -285.8 kJ/mol
By subtracting the sum of the reactants' enthalpies of formation from the sum of the products' enthalpies of formation, you can find the enthalpy change (∆H) for the reaction.
∆H = [∑∆Hf(products)] - [∑∆Hf(reactants)]
∆H = [1 * ∆Hf(CO2) + 2 * ∆Hf(H2O)] - [1 * ∆Hf(CH4) + 2 * ∆Hf(O2)]
∆H = [1 * (-393.5 kJ/mol) + 2 * (-285.8 kJ/mol)] - [1 * (-74.8 kJ/mol) + 2 * 0 kJ/mol]
∆H = -890.8 kJ/mol - (-74.8 kJ/mol)
∆H = -816 kJ/mol
Therefore, when one mole of methane is completely burned, it releases approximately 816 kJ (kilojoules) of energy.