Chemistry - Thermochemistry Question with Solution | TestHub
ChemistryThermochemistryEnthalpy of solution/dilution/hydrationEasy2 minQB
ChemistryEasysingle choice
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The thermal effects of reactions in liquid NH3 at -33°C were measured by observing the quantity of liquid NH3 vaporized by the process of interest. The heat of vaporization of NH3 at -33°C is 320.0 cal/g. When 1.07 g of NH4Cl was dissolved in 25 g of liquid NH3, 0.75 g of NH3 was vaporized. (Cl = 35.5)
The molar heat of solution of NH4Cl in liquid NH3 at this concentration is
Options:
Answer:
B
Solution:
Molar mass of NH4Cl = 14 + 4 + 35.5 = 53.5 g/mol, so 1.07 g = 0.0200 mol. Heat absorbed by vaporization = 0.75 × 320 = 240 cal, supplied by the dissolution, so it is exothermic. ΔH = -240/0.0200 = -12,000 cal/mol = -12.0 kcal/mol. Ans (b).
Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of solution/dilution/hydration
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