Buffer Solutions and Their Functions

What does a higher pKa value indicate about an acid?

When [A–][H+] is greater than [HA], the Ka value is low.

What is the formula for the Henderson-Hasselbalch equation?

The formula for calculating pKa is ___

Match the following items with their definitions:

What is the primary role of a buffer solution?

A buffer solution can be formed by any combination of acids and bases.

Name one application of buffer solutions.

An acidic buffer is prepared by mixing a weak acid and its ____ with a strong base.

Match the types of buffers to their pH characteristics:

Which statement is true about a buffer solution?

Buffer solutions can neutralize small amounts of added acids or bases without significant changes in pH.

What is the pH of an aqueous solution containing equal concentrations of acetic acid and sodium acetate?

Which of the following is an example of an acidic buffer solution?

An alkaline buffer solution is made by mixing a weak base and a strong base.

What is the pH of the acidic buffer solution made of sodium acetate and acetic acid?

A mixture of _______ and ammonium chloride forms an alkaline buffer solution.

Match the following terms with their definitions:

What does a high pKa value indicate about an acid?

Strong acids totally break down into their ions in aqueous solutions.

What is the pH of the alkaline buffer solution consisting of ammonium hydroxide and ammonium chloride?

Buffers maintain pH by neutralizing small amounts of added acids or bases.
A buffer requires both an acid to react with added hydroxide (OH⁻) and a base to react with added hydronium (H₃O⁺).
Composed of a mixture of a weak acid and its conjugate base or a weak base with its conjugate acid.

Resist changes in pH during dilution or addition of acids/bases.
Crucial in biological processes, including fermentation, food preservation, drug delivery, and enzyme activity.
Blood requires specific pH levels for optimum oxygen carrying capacity.

Acidic Buffers:
- Maintain acidic environments with pH below 7.
- Formed by mixing a weak acid with its salt (e.g., acetic acid and sodium acetate).
- Example: Aqueous solution of acetic acid and sodium acetate has a pH of 4.74.
Alkaline Buffers:
- Maintain basic conditions with pH above 7.
- Created by mixing a weak base with its salt (e.g., ammonium hydroxide and ammonium chloride).
- Example: Aqueous solution of ammonium hydroxide and ammonium chloride has a pH of 9.25.

pH: Indicates acidity or alkalinity of a solution.
pKa: Represents the pH at which a species can donate or accept a proton; defined as the negative logarithm of the acid dissociation constant (Ka).
Weak acids have higher pKa; strong acids have lower pKa.

Strong acids completely dissociate in aqueous solutions, while weak acids only partially dissociate.
High pKa indicates weak acid; low pKa indicates strong acid.
The relationship between [A⁻][H⁺] and [HA] helps determine the acid's strength.

Relates pH to pKa for buffer solutions.
Formula:
- pH of acid buffer = pKa + log ([base]/[acid])
- pKa = -log[Ka]
Enables calculation of pH when concentrations of acid and conjugate base are known.

Practice problem: Calculate the pH of a buffer solution with 0.3M acetic acid (Hac) and 0.3M sodium acetate (NaAc) using Ka of acetic acid (1.8x10⁻⁵).