In reverse electrolysis, 2 kg of hydrogen (H₂) and 1 kg of oxygen (O₂) are combined to form water (H₂O) while releasing energy. The energy released in this reaction can be calculated using the enthalpy of formation of water and the stoichiometry of the reaction.
The balanced chemical equation for the reverse electrolysis reaction is:
2H₂ + O₂ → 2H₂O
The enthalpy of formation of water is -286 kJ/mol. To calculate the energy released, we need to convert the masses of hydrogen and oxygen into moles. The molar mass of hydrogen (H₂) is 2 g/mol, and the molar mass of oxygen (O₂) is 32 g/mol.
Number of moles of hydrogen = 2000 g / 2 g/mol = 1000 mol Number of moles of oxygen = 1000 g / 32 g/mol = 31.25 mol
From the balanced equation, we can see that 2 moles of hydrogen react with 1 mole of oxygen to form 2 moles of water. Therefore, the number of moles of water formed will be equal to the number of moles of hydrogen.
Number of moles of water = 1000 mol
Now, we can calculate the energy released:
Energy released = Enthalpy of formation of water × Number of moles of water = -286 kJ/mol × 1000 mol = -286,000 kJ
The negative sign indicates that the reaction releases energy. Therefore, in the reverse electrolysis of 2 kg of hydrogen and 1 kg of oxygen, approximately 286,000 kJ of energy would be produced.