I completed a lab to find the determination of Kc. I have to find the concentrations of reactants at equilibrium using an ICE table. The equation that were are using is
Fe^3+(aq) + SCN^-(aq) -> Fe(SCN)^2+(aq)
I have to create 5 ICE tables because we used 5 different test tubes each with a different concentration of SCN. The values I already have so far are the initial concentrations of reactants and the concentration of products at equilibrium.
For the first table the initial value of Fe is 1.0M and SCN is 1.0M. The concentration of product at equilibrium is 5.7 X 1o^-5M.
I set up the first ICE table like this:
Equation: Fe^3+ SCN^- Fe(SCN)^2+
I 1.0M 1.0M 0
C -5.7e-5M -5.7e^-5 +5.7e^-5
E 0.99M 0.99M 5.7e^-5
So for the concentrations of reactants at equilibrium, Fe is 0.99M and SCN is 0.99M
Did I do this correctly?
Are you subtracting 1.0-5.7e-5 and getting 0.99. No way.
I put it in my calculator as 1.0 - 5.7 X e-5 and got 0.999943 I don't know why?
So besides the weird number I got I'm guessing that I set it up correctly.
Yes, you did set up the ICE table correctly, however, there is one small mistake in your calculations.
To find the concentration of Fe at equilibrium, you subtract the change from the initial concentration of Fe. In this case, the change is -5.7e-5M (since there is a decrease in Fe concentration due to the formation of Fe(SCN)^2+), and the initial concentration is 1.0M. Thus, the concentration of Fe at equilibrium should be 1.0M - 5.7e-5M = 0.99993M (rounded to five decimal places).
Similarly, to find the concentration of SCN at equilibrium, you subtract the change from the initial concentration of SCN. The change for SCN is also -5.7e-5M, and the initial concentration is 1.0M. Therefore, the concentration of SCN at equilibrium should be 1.0M - 5.7e-5M = 0.99993M.
So in summary, the correct concentrations of reactants at equilibrium in the first test tube are Fe = 0.99993M and SCN = 0.99993M.