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I have a doubt, kindly clarify. - The reaction, , for whichkJ mol-1andmol-1, is not feasible at 298 K. Temperature above which - Chemical Thermodynamics - JEE Main

The reaction, 

MgO(s)+ C(s)\rightarrow Mg(s)+CO(g), for  which \Delta _{r}H^{o}= + 491.1 kJ mol-1 and \Delta _{r}S^{o}= 198.0 \: JK^{-1} mol-1 , is not feasible at 298 K. Temperature above which reaction will be feasible is :

  • Option 1)

    2380.5 K 

  • Option 2)

    2480.3 K

  • Option 3)

    2040.5 K 

  • Option 4)

    1890.0 K 

Answers (1)
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ΔG{reaction} -

\Delta G _{reaction }= \sum \Delta G_{product}- \sum \Delta G_{reactant}
 

- wherein

\sum \Delta G_{product}=Sum of   \Delta G of all product

\sum \Delta G_{reactant}=Sum of   \Delta G of all reactant

 

 

Gibb's free energy (Δ G) -

\Delta G= \Delta H-T \Delta S
 

- wherein

\Delta G= Gibb's free energy

\Delta H= enthalpy of reaction

\Delta S= entropy

T= temperature

 

 

Spontanous process -

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

 

- wherein

For spontanouse process \Delta G must be negative.

\Delta H-T\Delta S<O

T>\frac{\Delta H}{\Delta S}

T>\frac{491.1\times 1000}{198}

T>2480.3 K

 


Option 1)

2380.5 K 

Option 2)

2480.3 K

Option 3)

2040.5 K 

Option 4)

1890.0 K 

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