# Equilibrium constants

Hi, can someone help me on the following question.

Equilibrium constant=0

Equilibrium constant=1

What are the significance of these 2 values? As in, what is happening to the reactants as well as the products in this 2 instances? Thank you!!

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Borek
Mentor
Write any reaction equation (even as simple as A <-> B), write expression for its equilibrium constant. Then it is simple math - think when equilibrium constant can equal 0 and when it can can equal 1, think in terms of values of concentrations of products and reactants.

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But what do the numbers means?

Eg. a + b $$\Updownarrow$$ c + d

Kc = [c][d]/[a]

Kc = 1 will mean [c][d] = [a]

Kc = 0 will mean either [c] is zero or [d] is zero

1. Is the enthaply change for the reaction zero?
2. Is there no reaction?
3. Is the activation energy zero?

Borek
Mentor
Let's start with the second case. If you start with a and b - what does it mean if c or d is zero? Think about the reaction stichiometry. If c is zero - what about d? How did a and b changed?

That means the other product should have zero concentration. Which also means no reaction would have taken place. Oh okok, thanks a lot, really!!

Then in the case for Kc = 1, amount of reactant is equal to the product. That means half of the reactants have been converted into the product, and the reaction has just reached dynamic equilibrium. So can i say it's just a normal equilibrium reaction. Thanks

Borek
Mentor
So can i say it's just a normal equilibrium reaction.
Sure you can, but it won't hurt to analyse it a little bit further. Think what it does mean when Kc > 1 or Kc < 1. Where the equilibrium lies - on the left, on the right? Kc = 1 doesn't have any special meaning, but it happens to be a border case.

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