Chemistry-Hess's Law
NEET Chemistry Hess's Law MCQ Question
Type: MCQ-numerical-Medium-Class 11
Given the reaction: C(s) + O2(g) → CO2(g) with a standard enthalpy change of -393.5 kJ/mol, what is the enthalpy change for the reaction 2CO2(g) → 2C(s) + 2O2(g)?
A
+393.5 kJ/mol
B
+787.0 kJ/mol
C
-393.5 kJ/mol
D
-787.0 kJ/mol
Correct Answer
Option B
Detailed Explanation
According to Hess's Law, reversing a reaction changes the sign of the enthalpy change. Since the original reaction is exothermic with -393.5 kJ/mol, reversing and doubling it gives +787.0 kJ/mol.
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