Equilibrium rice table

Question

K = 49 for the following gas phase reaction at 450oC. H2 + I2 ⇔ 2HI

If 1.00 mole of HI is put into an evacuated 1.00-liter container and allowed to reach equilibrium

enter the equilibrium value for the concentration of HI (g):

Answer 1

Reaction   H2   +   I2   <--->    2HI

Initial         0          0              1.00 

Change    +x        +x            -2x

Equilib      x          x              1.00 - 2x

 

K = [HI]² / [H₂][I_2] = 49

49 = (1.00 - 2x)² / (x)(x)

49 = (1.00 - 2x)² / x²

7 = 1.00 - 2x / x

7x = 1.00 - 2x

9x = 1.00

x = 0.111

 

Equilibrium [HI] = 1.00 - 2x = 1.00 - 2x0.111 = 1.00 = 0.222 = 0.778 M