Equilibrium Constant & Temperature (1 Viewer)

[_Anonymous]

Why does the equilibrium constant get affected only by changes in temperature? Why not with changes in pressure or concentration?

Let's consider a general reaction: A + B <--> C + D where Δ < 0

The eq. constant expression would be [C][D]/[A]. If we were to increase the temperature, equilibrium would shift left, meaning [products] would decrease but [reactants] would increase. Doesn't this change balance out the eq. expression and thus the value for K shouldn't change?

 

[jazz519]

This effect that only temperature can change the K value is best visualised through concentration vs time graphs.

You can test this for yourself but when you increase the pressure for example. This means volume decreases as they are inversely proportional as such the concentration of everything will end up increasing in C = n/v

Now you will see the equilibrium shifting a certain way, but in the end if you try calculate the equilibrium constant with the new concentrations you will see although the numbers for concentrations have changed the equilibrium constant remains the same as it is a ratio

A similar concentration vs time graph can be drawn for adding or removing components and you will see the exact same effect