How much `CH_3COONa` should be added to 1 litre of 0.1 M `CH_3COOH` to make a buffer of pH=4.0 ? `K_a=1.8xx10^(-5)`

Explanation

To determine how much sodium acetate (CH₃COONa) should be added to 1 liter of 0.1 M acetic acid (CH₃COOH) to achieve a buffer solution with a pH of 4.0, we can use the Henderson-Hasselbalch equation:

\[ \text{pH} = \text{pK}_a + \log\left(\frac{[\text{A}^-]}{[\text{HA}]}\right) \]

Where:
- \(\text{pH}\) is the desired pH of the buffer solution.
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