In the dissociation of HI, it is found that 20% of the acid is dissociated when equilibrium is reached. Calculate the pressure equilibrium constant.

Explanation

To calculate the pressure equilibrium constant \( K_p \) for the dissociation of hydrogen iodide (HI), we can follow these steps:

### Step 1: Write the balanced chemical equation
The dissociation of hydrogen iodide can be represented as:
\[ 2 \text{HI} \rightleftharpoons \text{H}_2 + \text{I}_2 \]

### Step 2: Define initial conditions
Assume the initial pressure of HI is \( P \).
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