Chemistry - Thermochemistry Question with Solution | TestHub
ChemistryThermochemistryEnthalpy of CombustionMedium2 minQB
ChemistryMediumsingle choice
Passage / Comprehension
When 0.1 mole of C8H18(l) at 300 K is completely burned at constant pressure in some oxygen gas at 300 K, yielding products gaseous H2O, CO and CO2 at 800 K, the process yielding 87.3 kcal of heat to the surrounding. Given:
Δf H (kcal/mol): C8H18(l) = -74.0, CO2(g) = -94.0, CO(g) = -26.5, H2O(g) = -58.0
Molar heat capacity at constant pressure (cal/K-mol): CO(g) = 7.0, CO2(g) = 8.0, H2O(g) = 6.0
Assume that all Δr H are independent of temperature.
How many moles of H2O are produced?
Options:
Answer:
B
Solution:
Each C₈H₁₈ molecule has 18 H atoms, which can form 9 H₂O molecules. For 0.1 mol of C₈H₁₈, the amount of H₂O produced is 0.1 × 9 = 0.9 mol. This corresponds to option (b).
Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Combustion
⏱ 2mℹ️ Source: QB
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