The data below refer to the following reaction: 2NO(g) + I2(g) 2NOI(g) Concentration (M) [NO] [I2] [NOI] Initial 2.0 4.0 1.0 Equilibrium 1.0 — — Find the concentration of I2 when the system reaches equilibrium.

3.5 mol·L⁻¹  

Explanation:

1. Set up an ICE table.

2. Solve for x

The equilibrium concentration of NO is 1.0 mol·L⁻¹, so

       1.0 = 2.0 - 2x

2x + 1.0 = 2.0

        2x =  1.0

          x = 0.5

3. Calculate the equilibrium concentration of I₂

[I₂] = 4.0 - x = 4.0 - 0.5 = 3.5 mol·L⁻¹

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