Calculate the concentration of `H_(3)O^(+)` ions in a mixture of 0.02 M acetic acid and 0.2 M sodium acetate. Given that the ionization constant `(K_(a))` for acetic acid is `1.8xx10^(-5)`.

Explanation

To calculate the concentration of \( H_3O^+ \) ions in a mixture of 0.02 M acetic acid and 0.2 M sodium acetate, we can use the Henderson-Hasselbalch equation, which is applicable for buffer solutions.

### Step-by-Step Solution:

1. **Identify the Components**:
- Acetic acid (\( CH_3COOH \)) is a weak acid.
- Sodium acetate (\( CH_3COONa \)) is the salt of the weak acid and provides the conjugate base (\( CH_3COO^- \)).

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