In an experiment, 2.0 moles of NOCl was placed in a one-litre flask and the concentration of NO after equilibrium established, was found to be 0.4 mol/L. The equilibrium constant at 30 C is _____ x 10

Question

In an experiment, 2.0 moles of NOCl was placed in a one-litre flask and the concentration of NO after equilibrium established, was found to be 0.4 mol/L. The equilibrium constant at 30 C is _____ x 10 o –4

Prashant Kotian · Accepted Answer

Correct answer: 125. **Step 1: Write the balanced equation and ICE table** 2NOCl(g) ⇌ 2NO(g) + Cl₂(g) | | 2NOCl | 2NO | Cl₂ | |---|---|---|---| | Initial | 2.0 M | 0 | 0 | | Change | -2x | +2x | +x | | Equilibrium | 2.0-2x | 2x | x | **Step 2: Find x using the given NO concentration** At equilibrium: [NO] = 2x = 0.4 mol/L Therefore: x = 0.2 mol/L **Step 3: Calculate equilibrium concentrations** - [NOCl] = 2.0 - 2(0.2) = 1.6 M - [NO] = 0.4 M - [Cl₂] = 0.2 M **Step 4: Apply equilibrium constant expression** Kc = [NO]²[Cl₂] / [NOCl]² **Step 5: Substitute values and calculate** Kc = (0.4)² × (0.2) / (1.6)² Kc = (0.16 × 0.2) / 2.56 Kc = 0.032 / 2.56 = 0.0125 **Step 6: Express in scientific notation** Kc = 0.0125 = 1.25 × 10⁻² = 125 × 10⁻⁴ Therefore, the answer is 125.

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