pH and Henderson-Hasselbalch Equation

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Questions and Answers

What does the dissociation constant of water (Kd) express?

The relationship between the pH of a solution and its temperature

The relationship between the hydrogen ion concentration, the hydroxide ion concentration, and the concentration of water at equilibrium (correct)

The strength of an acid in a solution

The relationship between the hydrogen ion concentration and the hydroxide ion concentration

What is the condition in which the body fluids have excess base (alkali)?

Acidosis

Homeostasis

Alkalosis (correct)

Neutralosis

What is the purpose of the Henderson-Hasselbalch equation?

To estimate the pKa value of an acid

To describe the behavior of weak acids and buffers (correct)

To calculate the pH of a strong acid solution

To determine the buffer capacity of a solution

What does a lower pKa value indicate about an acid?

The acid is stronger and more fully dissociated in water Signup and view all the answers

What is the function of buffers in the body?

To maintain a constant pH in the body's fluids Signup and view all the answers

What is the main characteristic of strong acids?

They dissociate completely in solution Signup and view all the answers

What is the primary function of electrolytes in the body?

To balance the amount of water in the body and maintain acid-base levels Signup and view all the answers

What is the Henderson-Hasselbalch equation used to describe?

The quantitative relationship between the pH of a solution and the concentration of a weak acid and its conjugate base Signup and view all the answers

What is the pH of a solution with a hydrogen ion concentration of 10^(-7) mol/l?

7 Signup and view all the answers

What is the definition of an acid?

A compound that donates a hydrogen ion Signup and view all the answers

At what pH does the maximum buffering capacity occur?

A pH equal to the pKa Signup and view all the answers

What is the primary location of the bicarbonate-carbonic acid buffer system?

Extracellular fluid (ECF) Signup and view all the answers

What is the normal pH range of blood?

7.36-7.44 Signup and view all the answers

What is the role of hemoglobin in the blood?

It cooperates with the bicarbonate buffer system to buffer the blood and transport CO2 Signup and view all the answers

What is the function of the phosphate buffer system in the body?

To buffer the pH of the intracellular fluid (ICF) Signup and view all the answers

Study Notes

pH and Water

Neutral pH of water is maintained by the dissociation constant of water (Kd), which expresses the relationship between hydrogen ion concentration, hydroxide ion concentration, and the concentration of water at equilibrium.
pH is the negative log of the hydrogen ion concentration, expressed in mole per liter (mol/L).

Henderson-Hasselbalch Equation

Describes the behavior of weak acids and buffers.
Derives the pH as a measure of acidity in biological and chemical systems.
Used for estimating the pH of a buffer solution and finding the equilibrium pH in acid-base reactions.

Acids and Bases

Strong acids have a larger Ka value and dissociate completely in solution, whereas weak acids have a smaller Ka value and dissociate only partially.
A lower pKa value indicates a stronger acid, which fully dissociates in water.
Acidosis is a process causing increased acidity in the blood and other body tissues, while alkalosis is a condition where the body fluids have excess base (alkali).

Buffers

Buffers, consisting of a weak acid and its conjugate base, resist changes in pH when hydrogen ions or hydroxide are added.
Buffer capacity is the maximum amount of strong acid or strong base that can be added before a significant change in pH occurs.

Water and Thermal Regulation

The structure of water allows it to resist temperature changes.

Electrolytes

Electrolytes are minerals in the body that have an electric charge and help balance the amount of water in the body and maintain the body's acid-base level.

Strong and Weak Acids

Inorganic acids like sulfuric acid and hydrochloric acid are strong acids that dissociate completely in solution.
Organic acids, containing carboxylic acid groups, are weak acids that dissociate only partially in water.

Buffer Systems in the Body

The major buffer systems in the body include the bicarbonate-carbonic acid buffer system, the hemoglobin buffer system, the phosphate buffer system, and the protein buffer system.

Metabolic Acids and Buffers

Metabolic activity produces roughly 22,000 mEq of acids per day.
The pH of blood is normally maintained between 7.36-7.44.

Bicarbonate Buffer System

The bicarbonate buffer system operates principally in the extracellular fluid (ECF).
The enzyme carbonic anhydrase is involved in the reaction.

Phosphate Buffer System

The phosphate buffer system operates in the intracellular fluid (ICF).
The reaction involves the conversion of H2PO4- to HPO42-.

Protein Buffer System

The protein buffer system operates in cells and plasma.

Urinary Hydrogen, Ammonium, and Phosphate Ions

Nonvolatile acids from metabolism cannot be excreted as expired CO2 and are excreted in the urine.
The pH of urine is 5.5-7.0.
Urinary ions include phosphate, ammonium, uric acid, dicarboxylic acid, citric acid, and sulfuric acid.