Chemistry - Thermochemistry Question with Solution | TestHub
ChemistryThermochemistryEnthalpy of ReactionMedium2 minQB
ChemistryMediumsingle choice
Ethyl bromide is prepared by the reaction:
C2H4(g) + HBr(g) → C2H5Br(g); ΔH = -84 kJ
What is the value of ΔU (in kJ) if 56 g of ethylene and 162 g of HBr are allowed to react? (Assume 298 K.)
Options:
Answer:
A
Solution:
Moles: C2H4 = 56/28 = 2 mol and HBr = 162/81 = 2 mol, so 2 mol of reaction occurs. Per mole of reaction Δng = 1 - 2 = -1, giving ΔU = ΔH - Δng RT = -84 + (8.314 × 298)/1000 = -84 + 2.48 = -81.52 kJ. For 2 mol: ΔU = 2 × (-81.52) = -163.0 kJ. This is option (a).
Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Reaction
⏱ 2mℹ️ Source: QB
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