The value of the equilibrium constant?

Question

0.450 mol of hydrogen bromide gas decomposes in a 0.75 L container according to the reaction below:

2 HBr_(g)  ↔ H_2(g) +  Br_2(l)

At equilibrium the concentration of H_2(g) was found to be 0.130 mol/L. The value of the equilibrium constant Kc is a.bc?

Write your answer for a.bc? in the blank, including the decimal.

Your Answer:

Answer 1

0.450 mol HBr/0.75 L = 0.6 M

2 HBr_(g)  ↔ H_2(g) +  Br_2(l) ... balanced equation

0.6.............0............0.........Initial.....

-0.26......+0.13....+0.13.....Change....

0.34........0.13.......0.13....Equilibrium...

K_c = [H₂][Br₂]/[HBr]²

K_c = (0.13)(0.13)/(0.34)² = 0.15