2 and 19 please! solubility of hydroxyapatite in a buffered aqueous solution wit

Question

2 and 19 please!

solubility of hydroxyapatite in a buffered aqueous solution with pH = SECTION 17.1: THE COMMON ION EFFECT Review Questions VC 17.2 Consider the [CH COOH 4.74. How doubled the a) The pH b) The pH c) The ph VC 17.3 Consider in which 0.75 M causin a) HC VC 17.4 Acco stron 17.1 Use Le Châtelier's principle to explain how the common ion effect affects the pH of a weak acid solution. Describe the effect on pH (increase, decrease, or no change) that results from each of the following additions: (a) potassium acetate to an acetic acid solution, (b) ammonium nitrate to an ammonia solution, (c) sodium formate (HCOONa) to a formic acid 17.2 (HCOOH) solution, (d) potassium chloride to a hydrochloric acid solution, (e) barium iodide to a hydroiodic acid solution. Define pK, for a weak acid. What is the relationship 17.3

Explanation / Answer

2a) Consider the ionization of acetic acid (HOAc) as below.

HOAc (aq) <=====> H+ (aq) + OAc- (aq)

The acid ionization constant is given as

Ka = [H+][OAc-]/[HOAc]

Potassium acetate (KOAc) ionizes as below.

KOAc (aq) -------> K+ (aq) + OAc- (aq)

The addition of KOAc to a solution of HOAc increases [OAc-]. However, Ka is equilibrium constant and must remain constant at a particular temperature. Therefore, in order to keep Ka constant, [H+] must decrease. Now, the pH of a solution is defined as pH = -log [H+]. Therefore, a lower [H+] indicates a higher pH and viceversa. Since [H+] decreased due to the addition of KOAc to a solution of HOAc, hence, the pH of the solution increases.

2b) Consider the ionization of ammonia (NH3) as below.

NH3 (aq) + H2O (l) <=====> NH4+ (aq) + OH- (aq)

The base ionization constant is given as

Kb = [NH4+][OH-]/[NH3]

Ammonium nitrate (NH4NO3) ionizes as below.

NH4NO3 (aq) -------> NH4+ (aq) + NO3- (aq)

The addition of NH4NO3 to a solution of NH3 increases [NH4+]. However, Kb is equilibrium constant and must remain constant at a particular temperature. Therefore, in order to keep Kb constant, [OH-] must decrease. Now, the pOH of a solution is defined as pOH = -log [OH-]. Therefore, a lower [OH-] indicates a higher pOH and viceversa. Since [OH-] increased due to the addition of NH4NO3 to a solution of NH3, hence, the pOH of the solution increases. Now, the pH and the pOH of a solution are related as pH + pOH = 14. Therefore, the higher the pOH, the lower is the pH and hence, the pH of the solution in (b) decreases.

2c) Consider the ionization of formic acid (HCOOH) as below.

HCOOH (aq) <=====> H+ (aq) + HCOO- (aq)

The acid ionization constant is given as

Ka = [H+][HCOO-]/[HCOOH]

Sodium formate (HCOONa) ionizes as below.

HCOONa (aq) -------> Na+ (aq) + HCOO- (aq)

The addition of HCOONa to a solution of HCOOH increases [HCOO-]. However, Ka is equilibrium constant and must remain constant at a particular temperature. Therefore, in order to keep Ka constant, [H+] must decrease. Now, the pH of a solution is defined as pH = -log [H+]. Therefore, a lower [H+] indicates a higher pH and viceversa. Since [H+] decreases due to the addition of HCOONa to a solution of HCOOH, hence, the pH of the solution increases.

2d) Consider the ionization of hydrochloric acid (HCl) as below.

HCl (aq) --------> H+ (aq) + Cl- (aq)

HCl is a strong acid and ionizes completely. Therefore, the acid ionization constant, Ka >> 1. KCl ionizes to produce Cl-. However, since Ka >> 1, the addition of KCl to a solution of HCl has no effect on the pH of the solution. The pH therefore, remains constant.

2e) Consider the ionization of hydroiodic acid (HI) as below.

HI (aq) --------> H+ (aq) + I- (aq)

HI is a strong acid and ionizes completely. Therefore, the acid ionization constant, Ka >> 1. Barium iodide, BaI2 ionizes to produce I-. However, since Ka >> 1, the addition of BaI2 to a solution of HI has no effect on the pH of the solution. The pH therefore, remains constant.

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.