Answer: 238.6 J
Explanation:
1) Chemical energy is indicated as enthalpy
2) Energy balance:
∑ enthalpy of the reactants + energy added = ∑ enthalpy of the products + energy released.
3) ∑ enthalpy of the reactants = 85.1 J + 87.9 J = 173 J
4) energy added = 104.3 J
5) ∑ enthalpy of the products = 38.7 J + D
6) energy released = 0
7) Equation:
173J + 104.3J = 38.7 + D + 0
⇒ D = 173J + 104.3J - 38.7J = 238.6J, which is the chemical energy of the product D.
