NEETChemistryThermodynamics (C)
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): If the standard enthalpy of formation of CO ₂( g ) is -393.5 ~kJ~mol ⁻¹ , then the standard enthalpy change for the reaction 2 CO ₂( g ) 2 C ( graphite ) + 2 O ₂( g ) is +787.0 ~kJ . Reason (R): Enthalpy is an intensive property, so multiplying the stoichiometric coefficients of a reaction by an in
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
C. (A) is true but (R) is false
Step-by-step solution
Assertion (A) is true: The standard enthalpy of formation of CO ₂( g ) corresponds to the reaction: C ( graphite ) + O ₂( g ) CO ₂( g ) _ f H ^ = -393.5 ~kJ~mol ⁻¹ The given reaction is the reverse of the formation reaction, multiplied by a factor of 2: 2 CO ₂( g ) 2 C ( graphite ) + 2 O ₂( g ) Therefore, the enthalpy change for this reaction is: _ r H ^ = -(-393.5 ~kJ~mol ⁻¹) 2 = +787.0 ~kJ . Reason (R) is false: Enthalpy is an extensive property, meaning its value depends on the quantity of matter undergoing the