Final answer:
The provided information suggests that when the amount of product formed in a reaction is doubled, the change in enthalpy (ΔH°) is also doubled. Applying this principle, one could estimate the ΔH° for the decomposition of 2 moles of nitroglycerin; however, specific data for nitroglycerin is required for an accurate calculation.
Step-by-step explanation:
The question involves calculating the magnitude of ΔH° (change in standard enthalpy) for the decomposition of 2 moles of nitroglycerin at 25°C. According to the passage, the formation of 2 moles of NO₂ results in a ΔH of +66.4 kJ. Since enthalpy is an extensive property, it is proportional to the amount of substance involved in the reaction. Therefore, we can infer that if the decomposition of nitroglycerin is analogous to the provided equation for NO₂ formation, then the enthalpy change would be expected to be twice that of a single reaction event for 2 moles of the product formed.
However, the available information does not directly relate to nitroglycerin, but only provides an example of doubling enthalpy change with the quantity of reactants. To determine the actual ΔH° for nitroglycerin decomposition, we would need specific thermodynamic data for that reaction, which is not provided in the question. Therefore, the closest answer to the provided data would be an educated guess based on the principle that ΔH° is doubled when the amount of products is doubled.