Assertion : When a salt such as NaCl dissolve | vedclass

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Question

(C) In $NaCl$ crystal,$Na^{+}$ and $Cl^{-}$ ions are strongly held by electrostatic forces of attraction.When the salt dissolves,these ions leave the

Vedclass · Accepted Answer

If the Assertion is correct but Reason is incorrect.

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(C) In $NaCl$ crystal,$Na^{+}$ and $Cl^{-}$ ions are strongly held by electrostatic forces of attraction.When the salt dissolves,these ions leave the crystal lattice and enter the solution,thereby acquiring greater freedom (increased entropy).Thermodynamically,for a process to be spontaneous,the change in Gibbs free energy,$\Delta G = \Delta H - T\Delta S$,must be negative.For the dissolution of $NaCl$,the enthalpy change $\Delta H$ is positive (endothermic),but the entropy change $\Delta S$ is positive,making the term $T\Delta S$ large and positive.Since $T\Delta S > \Delta H$,the value of $\Delta G$ becomes negative,making the process spontaneous.The reason statement claims $\Delta H$ is highly positive and $T\Delta S$ is a low negative value,which is incorrect as $T\Delta S$ is actually positive for this process.Thus,the Assertion is correct,but the Reason is incorrect.

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