JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry

For a given chemical \(A \rightarrow B\) at \(300\, \mathrm{~K}\) the free energy change is \(-49.4\, \mathrm{~kJ} \,\mathrm{~mol}^{-1}\) and the enthalpy of reaction is \(51.4\, \mathrm{~kJ} \,\mathrm{~mol}^{-1}\). The entropy change of the reaction is \(.....\,\mathrm{J}\, \mathrm{K}^{-1}\, \mathrm{~mol}^{-1} .\)

A \(360\)
B \(390\)
C \(460\)
D \(551\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(360\)

Step-by-step Solution

Detailed explanation

Given chemical reaction: \(\mathrm{A} \underset{\mathrm{T}\, 300\, \mathrm{~K}}{\longrightarrow} \mathrm{B}\) \([\Delta \mathrm{G}]_{\mathrm{P}, \mathrm{T}}=-49.4\, \mathrm{~kJ} / \mathrm{mol}\) \(\Delta \mathrm{H}_{\mathrm{rxn}}=51.4 \,\mathrm{~kJ} / \mathrm{mol}\)…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match List\(-I\) with List\(-II\)

List\(-I\)	List\(-II\)
\((A)\) Spontaneous process	\((I)\,\Delta H < 0\)
\((B)\) Process with \(\Delta P =0 \;\Delta T =0\)	\((II)\,\Delta G _{ T , P } < 0\)
\((C)\,\Delta H _{reaction}\)	\((III)\) Isothermal and isobaric process
\((D)\) Exothermic process	\((IV)\) [Bond energies of molecules in reactants] - [Bond energies of product molecules]

Choose the correct answer from the options given below:

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Which of the following are isostructural pairs ? \(A.\) \(SO _{4}^{2-}\) and \(CrO _{4}^{2-}\) \(B.\) \(SiCl _{4}\) and \(TiCl _{4}\) \(C.\) \(NH _{3}\) and \(NO _{3}^{-}\) \(D.\) \(BCl _{3}\) and \(BrCl _{3}\) \(BCl _{3}\) and \(BrCl _{3}\)

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Match List\(-I\) with List\(-II\)

List\(-I\)	List\(-II\)
\((a)\) Phase difference between current and voltage in a purely resistive \(AC\) circuit	\((i)\) \(\frac{\pi}{2} ;\) current leads voltage
\((b)\) Phase difference between current and voltage in a pure inductive \(AC\) circuit	\((ii)\) zero
\((c)\) Phase difference between current and voltage in a pure capacitive \(AC\) circuit	\((iii)\) \(\frac{\pi}{2} ;\) current lags voltage
\((d)\) Phase difference between current and voltage in an \(LCR\) series circuit	\((iv)\) \(\tan ^{-1}\left(\frac{X_{C}-X_{L}}{R}\right)\)

Choose the most appropriate answer from the options given below:

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run	\([ NO ]_{0}\)	\(\left[ Cl _{2}\right]_{0}\)	\(r _{0}\)
\(1\)	\(0.10\)	\(0.10\)	\(0.18\)
\(2\)	\(0.10\)	\(0.20\)	\(0.35\)
\(3\)	\(0.20\)	\(0.20\)	\(1.40\)