The standard entropies of ${N_2}(g),\,\,{H_2}(g)$ and $N{H_3}(g)$ are $191.5,\,\,130.5,\,\,192.6\,\,\,{\rm{J}}{{\rm{K}}^{{\rm{ - 1}}}}\,{\rm{mo}}{{\rm{l}}^{{\rm{ - 1}}}}$. The value of $\Delta S^\circ $ formation of ammonia is

$ + 129.4\,J \cdot {K^{ - 1}} \cdot \,mo{l^{ - 1}}$

$ - 29.4\,J \cdot {K^{ - 1}} \cdot \,mo{l^{ - 1}}$

NEET UG CHEMISTRY MCQ: THERMODYNAMICS

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Application +4 | -1

The standard entropies of

{N_2}(g),\,\,{H_2}(g)

and

N{H_3}(g)

are

191.5,\,\,130.5,\,\,192.6\,\,\,\mathrm{J}{\mathrm{K}^{\mathrm{ - 1}}}\,\mathrm{mo}{\mathrm{l}^{\mathrm{ - 1}}}

. The value of

\Delta S^\circ

formation of ammonia is

View answer and explanation

Correct option: A

- 98.9\,J {K^{ - 1}} \,mo{l^{ - 1}}

Option A (-98.9 J K⁻¹ mol⁻¹) is correct because it is calculated using the standard entropies of the reactants and products for the formation of ammonia.

More Questions from THERMODYNAMICS

Practice All Chapter MCQs →

The internal energy of one mole of a gas is: An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If

{T_i}

is the initial temperature and

{T_f}

is the final temperature, which of the following statements is correct? For which of the process, ∆S is negative? The work done by a weightless piston in causing an expansion ∆V (at constant temperature), when the opposing pressure, P is variable, is given by: Assertion :- At constant pressure of the change

\mathrm{H}_2 \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{g})

work done is negative.

Reason :- During phase transition work done is always negative. For the reaction,

\mathrm{X}_2 \mathrm{O_4(l}) \longrightarrow 2 \mathrm{XO}_2(\mathrm{g}), \Delta U=2.1 \mathrm{~kcal}, \Delta S=20 \mathrm{~cal} \mathrm{~K}^{-1}

300 \mathrm{~K}

. Hence,

\Delta G