Exam 17: Additional Aspects of Acidbase Equilibria

Assuming no volume change on mixing,what mass of ammonium chloride should be added to 250.0 mL of 0.25 M aqueous ammonia to produce a solution of pH 10.70? (K_b for ammonia is 1.8 × 10^-5)

Mixing comparable amounts of a strong acid and its conjugate base will form a buffer.

What is the buffer range (for an effective 2.0 pH unit)for a benzoic acid/sodium benzoate buffer? [Ka for benzoic acid is 6.3 × 10^-5]

What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid (HCOOH)requires 29.80 mL of 0.3567 mol L^-1 NaOH(aq)? K_a =1.8 × 10^-4 For formic acid.

What is the pH of a solution prepared by mixing equal volumes of 0.10 M aqueous hydrochloric and 0.1 M aqueous hydrofluoric acid? (K_a for HF is 6.6 × 10^-4)

What factor governs the selection of an indicator for a neutralization titration?

What is the pH at the equivalence point of a weak base-strong acid titration if 20.00 mL of NaOCl(aq)requires 28.30 mL of 0.50 mol L^-1 HCl(aq)for complete neutralization? K_a = 3.0 × 10^-8 for HOCl.

What is the pH of a 1.0 M aqueous solution of Na₃AsO₄?(K_a1 = 6 × 10^-3,K_a2 = 1 × 10^-7,K_a3 = 3 × 10^-12)

methyl orange: red at pH < 3.1: orange at pH 3.1-4.4: yellow-orange above pH 4.4 Litmus: red at pH < 4.5: purple at pH 4.5-8.3: blue above pH 8.3 Thymol blue: yellow at pH < 8.0: green at pH 8.0-9.6: blue above pH 9.6 Trinitrobenzene: colorless at pH < 12: yellow at pH 12.0-1: orange above pH 14.0 Which of the pH indicators from the list above would be most appropriate for the titration of 0.30 M aqueous acetic acid (K_a = 1.8 × 10^-5)with 0.15 M aqueous sodium hydroxide?

Which condition characterizes the stoichiometric point of a neutralization titration?