How do I solve this equilibrium question?

Question

2HI (g)==> H2+I2

 

A) Write the expression  for the equilibrium constant Kc for the reaction.

 

B) What is [HI] at equilibrium?

 

C) Determine the equilibrium concentrations of H2 and I2

 

D) Calculate the value of the following  equilibrium constants at 700K.

 

1) Kc of the original reaction 

 

2) 4HI <==> 2 H2+2I2

Answer 1

You can certainly write the expression for the equilibrium constant (part A), but the rest of the question cannot be answered as there insufficient information given.

A.  Kc = [H₂][I₂]/[HI]²

B.  Rearrange above equation to solve for [HI]

C.  Rearrange above equation to solve for [H2] which is the same as [I2]

D.  Kp = Kc(RT)^∆n

E.  Kc original squared