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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: damillia on May 03, 2019, 03:49:32 pm

Title: Equilibrium constant
Post by: damillia on May 03, 2019, 03:49:32 pm
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?
Title: Re: Equilibrium constant
Post by: -_-zzz on May 03, 2019, 05:30:55 pm
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.