Two separate calorimetry trials are performed with identical 0.0100 mol samples at constant pressure:
• Trial A: NH₄Cl(s) → NH₄⁺(aq) + Cl⁻(aq) q₁ = +3.40 kJ
• Trial B: NH₄⁺(aq) + OH⁻(aq) → NH₃(aq) + H₂O(l) q₂ = −4.70 kJ
Using these data, what is the molar enthalpy change, ΔH, for the overall reaction
NH₄Cl(s) + OH⁻(aq) → NH₃(aq) + H₂O(l) + Cl⁻(aq)?
a) +340kJmol−1
b) −13.0kJmol−1
c) −130kJmol−1
d) +130kJmol−1