Equilibrium constant

[damillia]

Hi!

I recently received my equilibrium/ rates of reaction SAC back and lost 3 marks because I didn't include units on my Kc expressions. I'm not talking about the calculated value of Kc, but the expressions itself ([products]/[reactants]). My teacher claimed you will get marked down in the final exam if you don't use units on your Kc expression, but I can't find any resources backing this up (not even the Heinemann textbook?).

So my question is, do you need to include units in your Kc expression?

[-_-zzz]

Hi!

I recently received my equilibrium/ rates of reaction SAC back and lost 3 marks because I didn't include units on my Kc expressions. I'm not talking about the calculated value of Kc, but the expressions itself ([products]/[reactants]). My teacher claimed you will get marked down in the final exam if you don't use units on your Kc expression, but I can't find any resources backing this up (not even the Heinemann textbook?).

So my question is, do you need to include units in your Kc expression?

You 100% need to because it reflects the coefficients of the reactants/products in the equation that you used to calculate the Kc value. Remember that different equations for the same system under equilbrium can yield different Kc values.