Indicate whether each of the following statements is true or...

Indicate whether each of the following statements is true or false. If the statement is false, restate it to make it true. (a) The formate ion $\left(\mathrm{CHO}_{2}^{-}\right)$ concentration in $0.10 \mathrm{M}$ $\mathrm{HCHO}_{2}$ is the same as in $0.10 \mathrm{M} \mathrm{NaCHO}_{2}$ (b) A buffer can be destroyed by adding too much strong acid. (c) A buffer can be made up by any combination of weak acid and weak base. (d) Because $K_{\mathrm{a}}$ for $\mathrm{HCO}_{3}^{-}$ is $4.7 \times 10^{-11}, \mathrm{~K}_{\mathrm{b}}$ for $\mathrm{HCO}_{3}^{-}$ is $2.1 \times 10^{-4}$

Indicate whether each of the following statements is true or false. If the statement is false, restate it to make it true.
(a) The formate ion $\left(\mathrm{CHO}_{2}^{-}\right)$ concentration in $0.10 \mathrm{M}$ $\mathrm{HCHO}_{2}$ is the same as in $0.10 \mathrm{M} \mathrm{NaCHO}_{2}$
(b) A buffer can be destroyed by adding too much strong acid.
(c) A buffer can be made up by any combination of weak acid and weak base.
(d) Because $K_{\mathrm{a}}$ for $\mathrm{HCO}_{3}^{-}$ is $4.7 \times 10^{-11}, \mathrm{~K}_{\mathrm{b}}$ for $\mathrm{HCO}_{3}^{-}$
is $2.1 \times 10^{-4}$

Key Concepts

Buffer Solutions

A buffer solution is composed of a weak acid and its conjugate base, or a weak base and its conjugate acid, that work together to resist changes in pH upon the addition of small amounts of strong acid or strong base. This capability arises because the weak acid/base pair can neutralize added H+ or OH–, but only within a certain capacity; exceeding this capacity leads to a breakdown of the buffering action.

Weak Acid Equilibrium

Weak acids do not completely dissociate in water, establishing an equilibrium between the undissociated acid and the ions produced (H+ and its conjugate base). The extent of this dissociation is described by the acid dissociation constant (Ka), which is central in understanding the acid’s behavior in solution and its effect on pH.

Common Ion Effect

The common ion effect describes how the presence of an ion that is a part of the equilibrium of a weak electrolyte affects its dissociation. When a solution already contains one of the ions produced by the weak acid or base, the equilibrium shifts, generally reducing further ionization, which in turn affects the concentration of species in solution.

Salt Hydrolysis

Salt hydrolysis involves the reaction of ions from a dissolved salt with water, which can lead to the formation of either an acidic or basic solution. Salts derived from weak acids or bases can undergo hydrolysis to generate additional H+ or OH–, thereby altering the pH relative to a solution of the unhydrolyzed salt.

Equilibrium Constant Relationships

For conjugate acid-base pairs, there is a fundamental relationship between their dissociation constants: the product of the acid dissociation constant (Ka) and the base dissociation constant (Kb) equals the ionization constant of water (Kw). This relationship is essential in predicting and understanding the pH behavior of solutions containing such pairs, especially in buffer systems.

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