[lilcybergimp]

I am having problems on this problem:
The equilibrium constant K_c for the reaction H₂ (g) + I₂ (g) <-->
2HI (g) is 54.3. The initial concentrations of H₂, I₂ and HI is 0.00623 M, 0.00414 M and 0.0224 M. Calculate the concentrations of H₂, I₂ and HI
at equilibrium.


I just need to know how to set it up right. Here is what I  have:

K_c = 54.3 = [HI²]     =                  (2x)²
              ----------                    ------------------------
             [H₂][I₂]                            ( 0.00623 - x)(0.00414 - x)

Can anyone tell me if I am starting this problem out right?

[Borek]

Where is initial HI?

[justin122289]

When you set up your ICE chart, it looks something like this:

                  H₂(g)    +    I₂(g)   <-------->    2HI(g)
Initial         0.00623 M    0.00414 M       0.0224 M 
Change       -x                   -x                   +2x       
Equilibrium  0.00623-x)     (0.00414-x)    (0.0224+2x)

Set up the constant expression:

K_c=((0.0224+2x)/(0.00623-x)(0.00414-x))  =  54.3

I'm assuming that you are starting with only reactants. From this point, solving for x should be fairly simple algebra. I hope I helped.