AIPMT PRELIMS2009Chemistry-Thermochemistry
AIPMT PRELIMS 2009 Chemistry Bond Enthalpy MCQ Question
Type: MCQ-numerical-Hard-Class 11
From the following bond energies: H – H bond energy: 431.37 kJ mol⁻¹ C = C bond energy: 606.10 kJ mol⁻¹ C – C bond energy: 336.49 kJ mol⁻¹ C – H bond energy: 410.50 kJ mol⁻¹ Enthalpy for the reaction, H H H H | | | | C = C + H – H ⟶ H – C – C – H | | | | H H H H will be:
A
-243.6 kJ mol⁻¹
B
-120.0 kJ mol⁻¹
C
553.0 kJ mol⁻¹
D
1523.6 kJ mol⁻¹
Correct Answer
Option B
Detailed Explanation
The enthalpy change is calculated using bond energies: [(4 × 410.5) + 606.1 + 431.3] – [(6 × 410.5) + 336.49] = -120.0 kJ mol⁻¹.
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