Which of the following lines correctly show the temperature dependence of equilibrium constant K, for an exothermic reaction ?

Options

A. A and B
B. B and C
C. C and D
D. A and D

Answer

A

Explanation

According to van't Hoff equation
` (d In K)/(dT)= (DeltaH^(@))/(RT^(2))`
or in the integraated form, we have
In `K= -(Delta H^(@))/(RT) + " constant"`
Thus, a plot of K vs `1//T` will be linear with slope `=(DeltaH)^(@)/R)`
As the reaction is exothermic, ` DeltaH^(@) "is " -ve`. Hence slope should be + ve which is so for the plots A and B .`