Two separate calorimetry trials are performed with identical 0.0100 mol samples at…

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

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) +340  kJ mol−1+340\;\text{kJ\,mol}^{-1} (b) −13.0  kJ mol−1-13.0\;\text{kJ\,mol}^{-1} (c) −130  kJ mol−1-130\;\text{kJ\,mol}^{-1} (d) +130  kJ mol−1+130\;\text{kJ\,mol}^{-1}

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