JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
If \(3.365\) g of ethanol \((l)\) is burnt completely in a bomb calorimeter at \(298.15\) K, the heat produced is \(99.472\) kJ. The \(|\Delta H_f°|\) of ethanol at \(298.15\) K is ______ \(\times 10^2\) kJ mol\(^{-1}\). (Nearest integer)
Given: Standard enthalpy for combustion of graphite \(=-393.5\) kJ mol\(^{-1}\)
Standard enthalpy of formation of water \((l)=-285.8\) kJ mol\(^{-1}\)
Molar mass in g mol\(^{-1}\) of C, H, O are \(12\), \(1\) and \(16\) respectively
- A 3
- B 4
- C 5
- D 6
Answer & Solution
Correct Answer
(A) 3
Step-by-step Solution
Detailed explanation
Molar mass of ethanol (\(C_2H_5OH\)) \(= 2(12) + 6(1) + 16 = 46\) g mol\(^{-1}\) Number of moles of ethanol burnt, \(n = \dfrac{3.365}{46} = 0.07315\) mol Since the combustion occurs in a bomb calorimeter (constant volume), the heat produced corresponds to the change in internal…
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