Respuesta :
Answer:
Explanation: To calculate the enthalpy change (ΔH) for the reaction NO(g) + O(g) → NO2(g) using the given data, we need to apply the Hess's Law of constant heat summation. This law states that the total enthalpy change for a reaction is the same regardless of the number of steps taken to reach the final reaction.
Here's how we can calculate the ΔH for the given reaction step by step:
1. Reverse the second equation (O2(g) → 2O(g)) to get O(g) → 0.5O2(g) and change the sign of the enthalpy change to -495 kJ.
2. Multiply the reversed equation by 0.5 and the given equation for the first reaction (2O3(g) → 3O2(g) with -427 kJ) by 2 to cancel out O2 and get the desired reaction NO(g) + O(g) → NO2(g).
3. Add the two manipulated equations together to obtain the overall reaction:
2(2O3(g) → 3O2(g)) + 0.5(O(g) → 0.5O2(g)) + NO(g) → NO2(g).
4. Add up the enthalpy changes for the individual reactions to get the enthalpy change for the overall reaction:
2(-427 kJ) + 0.5(-495 kJ) + (-199 kJ) = -854 kJ - 247.5 kJ - 199 kJ = -1300.5 kJ.
Therefore, the ΔH for the reaction NO(g) + O(g) → NO2(g) is -1300.5 kJ.
