I understand what the equilibrium constant is, however when reading in my textbook it has occurred to me that I do not understand what it's actual use/importance is. One specification in my syllabus is "Understand the importance of the numerical value of Kc".

Thank you for any help.

I do not understand why this question has been put on hold. How can I demonstrate that I have put in an effort into understanding this question when I literally cannot find the answer on the internet or in any of my four textbooks? I have familiarised myself with Kc, however nowhere can I find it's importance, hence the reason that I ask the question.


$K$ is the value of $Q$ at equilibrium. The expression for $Q$ and $K$ are the same however $Q$ describes the state of a system and $K$ describes the system at equilibrium. Le Chatelier's principle tells us that a system that has $Q\neq K$ will approach $K$. When $Q$ is not $K,$ the system is not at equilibrium.

K tells you where an equilibrium lays. For a given reaction, if $K$ is larger than 1 than the equilibrium is towards the right. If $K$ is less than one then the equilibrium is towards the left.
For a simple equilibrium such as acid dissociation, the forward reaction's equilibrium constant is

$$K = \frac{[\ce{H+}][\ce{A-}]}{[\ce{HA}]}$$ so you can compare the strengths of acids by comparing the equilibrium constant. Since the $K$ of nitric acid is larger than the $K$ of hydrofluoric acid we know that it is a stronger acid.

Hope this helps!


Not the answer you're looking for? Browse other questions tagged or ask your own question.