Determine the pH of a buffer containing 0.12 M acetic acid (pKa = 4.76) and 0.078 M sodium acetate? (b) For 1.00 L of the buffer in part (a) of this question, estimate its buffer capacity if 14 mL of 1.0 M HCl is added to the buffer. (c) Calculate buffer capacity using the van Slyke equation and compare this value with the buffer capacity determined in part (b) of this question.
(a) Determine the pH of a buffer containing 0.12 M acetic acid (pKa = 4.76) and 0.078 M sodium acetate?
(b) For 1.00 L of the buffer in part (a) of this question, estimate its buffer capacity if 14 mL of 1.0 M HCl is added to the buffer.
(c) Calculate buffer capacity using the van Slyke equation and compare this value with the buffer capacity determined in part (b) of this question.
(d) (i) Calculate the pH of a 55 mg mL-1 solution of ascorbic acid (pKa = 4.17, M = 176.1 g mol-1). (ii) What is the degree of ionization (in %) of a 55 mg mL-1 solution of ascorbic acid at a pH of 2.0 and at a pH of 7.0? (iii) Briefly explain how the differences in ionization values arise between these two pH values.
(e) A 5% w/v solution of lignocaine hydrochloride (M = 270.79 g/mol) is prepared. The solubility of lignocaine (M = 234.34 g/mol), a weak organic base (pKa = 7.95 and M = 234.33 g/mol) is 3.81 mg/mL. Calculate the pH at which lignocaine will begin to precipitate out of this solution.
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