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Why is delta Z2 = 0??
According to Hess's Law the change in enthalpy for the reaction equals: delta H = sum (delta H) of products - sum (delta H) of reagents. For reagents and products of the following reaction: delta H (XY3) = -370 kJ / 2 = -185 kJ. delta H (XZ2) = -170 kJ / 2 = -85 kJ. delta H (Y2Z) = -280 kJ / 2 = -140 kJ. delta H (Z2) = 0 delta H (for the reaction) = 6*(-140 kJ) + 4*(-85 kJ) - 4*(-185)-0 = -840 kJ - 340 kJ + 740 kJ = -440 kJ. Answer: -440 kJ.
How do you solve this?