What do equilibrium constants tell us?

You may be wondering why the tutorial about what equilibrium constants are good for is after the tutorial about how to calculate them.  The answer for this is simple:  Because if you don’t know what they are, you can’t really understand what they mean. Fortunately, your knowledge is now to the point where you know what they are, so we can get going with all of this.

smart-guy

The company I use for clip art thinks that this is what a knowledgeable person looks like.  I’ll wait while you go put on a suit.

So, without further ado, let’s get going!


What Equilibrium Constants Mean

When you see an equilibrium constant, you probably think to yourself, “Hey, there’s a number!”  And if you see another one, you probably think to yourself, “Hey, there’s another number!”  This, of course, assumes that  you’ve got a lot of free time to look at numbers.

As it turns out, equilibrium constants tell us quite a bit about what’s going on with an equilibrium.  Check it out, using our example from the last tutorial:

ex2

  • If K is a lot bigger than 1, the reaction contains mostly products.  In our example, we can see that a huge value for K would correspond to a large concentration of C and small concentrations of A and B.  Our reaction, then, has mostly converted the A and B into the product, C.
  • If K is a lot smaller than 1, the reaction contains mostly reagents.  In our example, K can only be small if either C is very small or A and B are huge.  Either way, this means that the reaction hasn’t done much since it got started.
  • If K is 1, then there’s roughly the same amount of product and reagent.  This may, depending on the equation, be a little bigger or smaller for one or the other, but it’s about right.

And that’s it!


Image credits:

Suit guy with computer:  Image courtesy of Ambro at FreeDigitalPhotos.net

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