Answer:
318.1 J
Step-by-step explanation:
The reaction given is:
X + Y → W + Z
The chemical energy of the reaction (ΔU), is the variation of the chemical energy, so is the chemical energy of the products (UW and UZ) less the chemical energy of the reactants (UX and UY).
If the reaction loses the chemical energy, it must be negative, and the chemical energy that a substance contains, is positive.
ΔU = (UW + UZ) - (UX + UY)
-111.6 = (41.9 + UZ) - (199.3 +272.3)
-111.6 = 41.9 + UZ - 471.6
- UZ = - 429.27 + 111.6
-UZ = - 318.1
UZ = 318.1 J