The molar heat of solution of NH4Br in liquid at this concentration is — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

Heat absorbed by $NH_3$ vaporization = 0.25 g × 320 cal/g = 80 cal. Since vaporization occurs, the solution process is exothermic, releasing 80 cal of heat. Moles of NH4Br = 0.98 / 98 = 0.01 mol. Thus, heat released per mole = -80 cal / 0.01 mol = -8000 cal/mol = -8.0 kcal/mol.