Question

Gaseous hydrogen iodide is placed in a closed container at 425∘C, where it partially decomposes to hydrogen and iodine: 2HI(g)⇌H2(g)+I2(g) At equilibrium it is found that [HI]= 3.52×10−3 M , [H2]= 4.78×10−4 M , and [I2]= 4.78×10−4 M . You may want to reference ( pages 644 - 645) Section 15.5 while completing this problem. Part A What is the value of Kc at this temperature? Express the equilibrium constant to three significant digits

Answer 1

0.0184

Step-by-step explanation:

Let's consider the following reaction at equilibrium.

2 HI(g) ⇌ H₂(g) + I₂(g)

The concentration equilibrium constant (Kc) is equal to the product of the concentration of the products raised to their stoichiometric coefficients divided by the product of the concentration of the reactants raised to their stoichiometric coefficients.

Kc = [H₂] × [I₂] / [HI]²

Kc = (4.78 × 10⁻⁴) × (4.78 × 10⁻⁴) / (3.52 × 10⁻³)²

Kc = 0.0184