JEE Main · 2024 · 05 Apr 2024 · Shift 1 · Chemical Thermodynamics

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Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A): Enthalpy of neutralisation of strong monobasic acid with strong monoacidic base is always

- 57 kJ mol^{- 1}

Reason (R): Enthalpy of neutralisation is the amount of heat liberated when one mole of

H^{+}

ions furnished by acid combine with one mole of

^{-} OH

ions furnished by base to form one mole of water.
In the light of the above statements, choose the correct answer from the options given below.

(A)(A) is true but (R) is false
(B)Both (A) and (R) are true and (R) is the correct explanation of (A)✓ Correct
(C)(A) is false but (R) is true
(D)Both (A) and (R) are true but (R) is not the correct explanation of (A)

Answer: (B)

Solution

For a strong monobasic acid and a strong monoacidic base, complete dissociation means the only reaction is

H^{+} + O H^{-} \to H_{2} O

, whose enthalpy is a fixed value of about

- 57 kJ mol^{- 1}

; so (A) is true. The Reason correctly defines enthalpy of neutralisation as the heat released when one mole of

H^{+}

combines with one mole of

O H^{-}

to form one mole of water, which is exactly why the value is constant. Both true and (R) is the correct explanation of (A).

JEE Main · 2024 · 05 Apr 2024 · Shift 1 · Single correct option

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JEE Main · 2024 · 05 Apr 2024 · Shift 1 · Chemical Thermodynamics

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