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What does a higher pKa value indicate about an acid?
What does a higher pKa value indicate about an acid?
When [A–][H+] is greater than [HA], the Ka value is low.
When [A–][H+] is greater than [HA], the Ka value is low.
False
What is the formula for the Henderson-Hasselbalch equation?
What is the formula for the Henderson-Hasselbalch equation?
pH = pKa + log([base]/[acid])
The formula for calculating pKa is ___
The formula for calculating pKa is ___
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Match the following items with their definitions:
Match the following items with their definitions:
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What is the primary role of a buffer solution?
What is the primary role of a buffer solution?
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A buffer solution can be formed by any combination of acids and bases.
A buffer solution can be formed by any combination of acids and bases.
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Name one application of buffer solutions.
Name one application of buffer solutions.
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An acidic buffer is prepared by mixing a weak acid and its ____ with a strong base.
An acidic buffer is prepared by mixing a weak acid and its ____ with a strong base.
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Match the types of buffers to their pH characteristics:
Match the types of buffers to their pH characteristics:
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Which statement is true about a buffer solution?
Which statement is true about a buffer solution?
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Buffer solutions can neutralize small amounts of added acids or bases without significant changes in pH.
Buffer solutions can neutralize small amounts of added acids or bases without significant changes in pH.
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What is the pH of an aqueous solution containing equal concentrations of acetic acid and sodium acetate?
What is the pH of an aqueous solution containing equal concentrations of acetic acid and sodium acetate?
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Which of the following is an example of an acidic buffer solution?
Which of the following is an example of an acidic buffer solution?
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An alkaline buffer solution is made by mixing a weak base and a strong base.
An alkaline buffer solution is made by mixing a weak base and a strong base.
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What is the pH of the acidic buffer solution made of sodium acetate and acetic acid?
What is the pH of the acidic buffer solution made of sodium acetate and acetic acid?
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A mixture of _______ and ammonium chloride forms an alkaline buffer solution.
A mixture of _______ and ammonium chloride forms an alkaline buffer solution.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What does a high pKa value indicate about an acid?
What does a high pKa value indicate about an acid?
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Strong acids totally break down into their ions in aqueous solutions.
Strong acids totally break down into their ions in aqueous solutions.
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What is the pH of the alkaline buffer solution consisting of ammonium hydroxide and ammonium chloride?
What is the pH of the alkaline buffer solution consisting of ammonium hydroxide and ammonium chloride?
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Study Notes
Buffer Solutions
- 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.
Functions of Buffers
- 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.
Types of Buffer Solutions
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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 and pKa
- 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.
Acid-Dissociation and Strength
- 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.
Henderson-Hasselbalch Equation
- 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.
Example Calculations
- 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).
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Description
This quiz explores the concept of buffer solutions, detailing how they maintain pH levels by neutralizing small amounts of acids or bases. It covers the different types of buffers, their importance in biological processes, and their specific compositions.
