For a chemical reaction A B C DDelta rHtheta 80 kJ mol1... | null (Chemistry) | DivineJEE

Exam

Chemistry

For a chemical reaction A + B ⇌ C + D

(

{\Delta _r}{H^\Theta }

= 80 kJ mol^{$-$ 1}) the entropy change

{\Delta _r}{S^\Theta }

depends on the temperature T (in K) as

{\Delta _r}{S^\Theta }

= 2T (J K^{$-$ 1}mol^{$-$ 1}).

Minimum temperature at which it will become spontaneous is ___________ K. (Integer)

Correct Answer:

200

We know,

\Delta G^\circ = \Delta H^\circ - T\Delta S^\circ

For a reaction to be spontaneous

\Delta G^\circ < 0

\Rightarrow

\Delta H^\circ - T\Delta S^\circ < 0

\Rightarrow

T > {{\Delta H^\circ } \over {\Delta S^\circ }}

\Rightarrow

T > {{80000} \over {2T}}

\Rightarrow

2T² > 80000

\Rightarrow

T² > 40000

\Rightarrow

T > 200

The minimum temperature to make it spontaneous is 200 K.

Select an option to instantly check whether it is correct or wrong.

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