Question
Which of the following plots represents an exothermic reaction ?
A.
B.
C.
D.
Answer :
Solution :
We have the following relationship.
$$\ln \,{K_p} = - \frac{{\Delta H}}{{RT}} + {\text{constant}}$$
Now, if $$\Delta H$$ is $$ - ve,$$ Then the relation comes out to be :
$${\text{ln}}\,{{\text{K}}_p} = \frac{{\Delta H}}{{RT}} + {\text{constant}}$$
$$\therefore \,\,\ln \,{K_p}\,\,{\text{vs}}\,\frac{1}{T}$$ graph is similar to $$y = mx + c$$ where, $$m$$ and $$c$$ both are positive. So, the graph will be as shown.
We have the following relationship.
$$\ln \,{K_p} = - \frac{{\Delta H}}{{RT}} + {\text{constant}}$$
Now, if $$\Delta H$$ is $$ - ve,$$ Then the relation comes out to be :
$${\text{ln}}\,{{\text{K}}_p} = \frac{{\Delta H}}{{RT}} + {\text{constant}}$$
$$\therefore \,\,\ln \,{K_p}\,\,{\text{vs}}\,\frac{1}{T}$$ graph is similar to $$y = mx + c$$ where, $$m$$ and $$c$$ both are positive. So, the graph will be as shown.