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A buffer solution is prepared by dissolving 1.50 g each of sodium benzoate, C6H5COONa, and benzoic...

A buffer solution is prepared by dissolving 1.50 g each of sodium benzoate, C6H5COONa, and benzoic acid, C6H5COOH (Ka = 6.45 × 10-5), in 150.0 mL of solution. The molar mass of benzoic acid is 122.12 g/mol and that of sodium benzoate is 144.10 g/mol.

a) What is the pH of this buffer solution?

b) Which buffer component must be added to change the pH to 4.00? What mass of that component is required?

c) What volume of 2.0 M NaOH or 2.0 M HCl must be added to the original buffer in part a to change the pH to 4.00?

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