The chemical reaction involved is the decomposition of Hydrogen iodide gas into Hydrogen gas and Iodine gas. Starting with 0.900 mol of Hl in an evacuated 2.0-L flask and with Kc=0.014,

Question

what is the molar concentration of hydrogen iodide gas at equilibrium?

Answer 1

2HI(g) ==> H₂(g) + I₂(g) ... balanced equation

ICE table:

2HI(g) ==> H₂(g) + I₂(g)

0.45............0...........0.......Initial

-2x.............+x.........+x.......Change

0.45-2x.......x............x........Equilibrium

Write the equilibrium expression:

Kc = 0.014 = [H₂][I₂] / [HI]²

0.014 = (x)(x) / (0.45-2x)²

Use quadratic equation to solve for x:

x = 0.0473 M

Equilibrium [HI] = 0.45 - 2x = 0.45 - 0.0946 = 0.355 M

(be sure to check my math)