Final answer:
To find the energy released when 25.0 grams of H2O is formed, we can use the given enthalpy change and convert the mass of water to moles. The energy released is approximately -394.4 kJ.
Step-by-step explanation:
The question is asking for the amount of energy released (in kJ) when 25.0 grams of H2O is formed. To find this, we need to use the given enthalpy change (ΔH) for the reaction and convert the mass of water to moles. First, we can convert the grams of H2O to moles by dividing by the molar mass of water (18.015 g/mol). This gives us 1.387 mol.
Next, we can use the equation q = ΔH × n to calculate the heat released. Rearranging the equation, we have ΔH = q / n. Plugging in the values, we get ΔH = -394 KJ / 1.387 mol = -284.2 KJ/mol. Finally, multiplying ΔH by the number of moles (1.387 mol) gives us the energy released = -284.2 KJ/mol × 1.387 mol = -394.4 KJ.