Question

Determine the volumes of 0.10 M CH3COOH and 0.10 M CH3COONa required to prepare 10 mL of the following pH buffers. (Note: pka of CH3COOH=4.7)

pH 3.7

pH 4.7

pH5.7

Answer 1

1)

pH 3.7

Let V mL of 0.10 M acetic acid are mixed with 10-V mL of 0.10 M sodium acetate

From (1) and (2)

Hence, 9.1 mL of 0.10 M acetic acid are mixed with mL of 0.10 M sodium acetate

2)

pH 4.7

Let V mL of 0.10 M acetic acid are mixed with 10-V mL of 0.10 M sodium acetate

From (1) and (2)

Hence, 5 mL of 0.10 M acetic acid are mixed with mL of 0.10 M sodium acetate

3)

pH 5.7

Let V mL of 0.10 M acetic acid are mixed with 10-V mL of 0.10 M sodium acetate

From (1) and (2)

Hence, 0.9 mL of 0.10 M acetic acid are mixed with mL of 0.10 M sodium acetate

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