I tried to do it, but please check if it's right or not,

The equilibrium expression is:

 

2ICl -> I2 + Cl2

 

Kc is 4.8x10-6

Find out the equilibrium concentration of Cl2, if the initial concentration of ICl is 1.33 mol/L. There is no I2 or C2 initially present.

 

so...

Kc = [iCl] / ([i2] [Cl2])

Substituting gives:

 

4.8x10-6 = 1.33 - x / (x times x)

 

Next we arrive at this quadratic equation in standard form:

 

4.8x10-6x2 + x - 1.33 = 0

 

Using the quadratic formula, which is x = (- b ± square root[b2 - 4ac]) / 2a, we obtain:

 

x = (- 1 + square root[(1)2 - (4) (4.8x10-6) (-1.33)]) / 9.6x10-6

After suitable calculations, i got x = 1.33

 

strange tho,

 

thanx for looking over.

No, you have the wrong expression for Kc:

 

Kc = [i2] [Cl2] / [iCl]^2

 

(That's divided by the concentration of ICl squared - sorry about the formatting).

 

Because [i2] will be equal to [Cl2] you can simplify this by taking the square root:

 

[Cl2]/[iCl] = sqrt(Kc)

 

[Cl2] turns out to be 2.91 x 10^-3