1.Quinine is an alkaloid, or naturally occurring base, used to treat malaria. A 0.0015 M solution of quinine has a pH of 9.84. What is Kb of quinine? 2.What is the pH of a 0.20 M solution of ammonia in water (Kb= 1.8 x 105)?
1.Hydrofluoric acid (HF) has Ka= 6.8 x 10–4. What is Kbfor the fluoride ion? 2. Which of the following anions has the largest K b value: NO 3 – , PO 4 3 – , HCO 3 – ?
Chemistry 102 Chapter 15 38 ACID-BASE PROPERTIES OF SALT SOLUTIONS A salt is an ionic substance resulting from a neutralization reaction: Acid + Base Salt + Water The aqueous solution of a salt may be: basic, acidic, or neutral Reason: Soluble salts derived from weak acids or weak bases undergo hydrolysis (reaction with H 2 O) in aqueous solution. I. Salt of a strong base (NaOH) and a weak acid (HC 2 H 3 O 2 ) completely NaC 2 H 3 O 2 (aq) Na + (aq) + C 2 H 3 O 2 (aq) dissociated Na + (aq) + H 2 O (l) No Reaction H + H + C 2 H 3 O 2 (aq) + H 2 O (l) H C 2 H 3 O 2 (aq) + OH ( aq) Bronsted Bronsted Bronsted Bronsted base acid acid base NOTE: The resulting solution is basic This reaction is referred to as the Hydrolysis of the acetate (C 2 H 3 O 2 ) ion
Chemistry 102 Chapter 15 39 II. Salt of a weak base (NH 4 OH) and a strong acid (HCl) completely NH 4 Cl (aq) NH 4 + (aq) + Cl (aq) dissociated Cl (aq) + H 2 O (l) No Reaction H + H + NH 4 + (aq) + H 2 O (l) NH 3 (aq) + H 3 O + ( aq) Bronsted Bronsted
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