[skyhighlife]

Hi all, I am a relative novice to chemistry and have been going through questions on chemical equilibrium. Consequently I have attached two questions where I am a little unsure of my calculations and methods. 
I got a value of Kc = 0.0156 for Q2 and a value of Kc =16 for Q1 but in both questions I am unsure if I am correct and also a little unsure of my calculations re ICE tables. It would be great if someone could show me the proper way to do ICE tables.
Many thanks and well done on a great forum.

Q1.
Bromine monochloride disassociated on heating according to the equation

2BrCl <=> Br2 + Cl2

In an experiment 0.9 moles of  BrCl were heated in a 5 ltr vessel at a certain temperature until equilibrium was established. The amount of free chlorine in the mixture was found to be 0.4 moles
(1)   calculate the equilibrium constant Kc for the reaction
(2)   Is the value of the equilibrium constant for the reaction when represented by the equation
BrCl <=> ½ Br2 + ½ Cl2  is the same as that calculated above?


Q2.
One mole of hydrogen iodide was injected into a 1ltr flask at 4500 C. The following equilibrium was set up:
2HI <=> H2 + I2
it was found that 0.8 moles of HI were formed at equilibrium. Calculate Kc.

[JustinCh3m]

for Q1,

ICE Table:

2BrCl  <=>  Br2  +  Cl2
I: .45M         0          0
C: -2x          +x       +x
E: .45-x         x         x

From here, can you confirm your value for Kc?

And for part 2, realize that K' = (Kc)^1/2  -- NOT:   1/2(Kc)!!

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The above should help you with Q2 as well.  :-)