Equilibria chemistry
 

Other equilibrium changes

User Guide

Explaining the temperature effect

Using Le Chatelier's Principle is a very useful way of predicting the effect of temperature on an equilibrium but it doesn't explain why the changes happen. For an explanation we need to look at how the rates of the forward and back reaction are affected by temperature. Rates of reaction depend on the rate constant and this is where we need to start.

The explanation is quite complex and you may have to look through it several times.

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What is the key assumption that we make about Kc?

We assume that Kc depends on the ratio between the forward and reverse reactions \inline \dpi{100} K_{\textup{c}}= \frac{k_{\textup{f}}}{k_{\textup{b}}}

How is the rate constant linked to the activation enthalpy and temperature?

The rate constant is linked to the activation enthalpy and temperature via the Arrhenius equation \inline \dpi{100} k= Ae^{\frac{-E_{\textup{a}}}{RT}}

What does the value of Kc depend upon if the temperature is changed?

K c depends on the enthalpy change and the temperature.

 
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