Chemistry - Thermochemistry Question with Solution | TestHub
ChemistryThermochemistryEnthalpy of CombustionMedium2 minQB
ChemistryMediumnumerical
Only gases remains after 9.0 g of carbon is treated with 10 l of air at 380 K and 8.21 atm pressure. (Assume 19% by volume oxygen, 80% nitrogen, 1% carbon dioxide). Determine the amount of heat evolved (in kcal) under constant pressure. Enthalpies of formation of CO2(g) and CO(g) are -96.0 and -26.0 kcal/mol, respectively.
Answer:
37.00
Solution:
Moles of air = 8.21 × 10/0.0821 × 380 = 2.632 mol, so nO2 = 0.19 × 2.632 = 0.50 mol. Carbon = 9.0/12 = 0.75 mol. Let x mol C form CO2 and y mol form CO: x + y = 0.75 and x + y/2 = 0.50 (O2 balance), giving x = 0.25, y = 0.50. Heat evolved = 0.25 × 96 + 0.50 × 26 = 24 + 13 = 37 kcal. Answer: 0037.
Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Combustion
⏱ 2mℹ️ Source: QB
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