Acid, basic and buffer Flashcards
Describe the role of water in biological systems.
Water acts as a solvent inside and outside the cell, facilitating biochemical reactions and the transport of substances.
Define pH and its significance in biological fluids.
pH is a measure of the concentration of hydrogen ions (H+) in a solution, indicating its acidity or basicity, which is crucial for the proper functioning of cellular structures.
How is pH calculated from hydrogen ion concentration?
pH is calculated using the formula pH = -log
What is the pH of pure water and why is it considered neutral?
The pH of pure water is 7, which is considered neutral because it has equal concentrations of hydrogen ions [H+] and hydroxide ions [OH-].
Explain the implications of pH changes in biological systems.
Changes in pH to more acidic (pH < 7) or more basic (pH > 7) conditions can disrupt protein shape and function, affecting cellular processes.
Identify the characteristics of acidic and basic solutions based on pH.
Acidic solutions have a pH < 7 (high [H+]), while basic solutions have a pH > 7 (low [H+]).
What is the importance of maintaining pH within a specific range in cells?
Maintaining pH around 7 is essential for the proper functioning of proteins, which play critical roles as enzymes, transporters, and receptors.
Define acids and provide an example.
An acid is any molecule, ion, or chemical group that tends to release H+. An example of an acid is hydrochloric acid (HCl) or a carboxyl group (-COOH).
Define bases and provide an example.
A base is any ion, molecule, or chemical group that accepts H+. Examples of bases include hydroxide ions (OH-), ammonia (NH3), and amino groups (NH2).
What happens to pH when an acid is added to a solution?
When an acid is added to a solution, the concentration of H+ increases, causing the pH to decrease.
What happens to pH when a base is added to a solution?
When a base is added to a solution, the concentration of H+ decreases, resulting in an increase in pH.
Define the dissociation constant for weak acids and bases.
The dissociation constant (Ka) for weak acids and bases is less than 1, indicating that they are mainly undissociated at equilibrium.
How is the pH of a strong basic solution calculated?
The pH of a strong basic solution can be calculated using the concentration of hydroxide ions (OH-).
Explain the significance of the Ka value for HCl.
A Ka value greater than 1 indicates that HCl is mostly dissociated in solution, leading to a low concentration of undissociated HCl.
What is a buffer solution?
A buffer solution minimizes changes in pH when small amounts of strong acid or strong base are added, typically made by mixing a weak acid and its conjugate base.
How does a buffer maintain pH when acids are added?
When acids are added, the H+ ions react with the conjugate base in the buffer, preventing significant changes in pH.
What happens to pH when bases are added to a buffer solution?
When bases are added, the OH- ions react with H+ from the weak acid in the buffer, forming water and maintaining the pH.
Describe the Henderson-Hasselbalch equation.
The Henderson-Hasselbalch equation is pH = pKa + log10[A-]/[HA], used to calculate the pH of a buffer solution.
What is the significance of pKa in a buffer solution?
The pKa is the pH at which the concentrations of the acid (HA) and its conjugate base (A-) are equal, providing maximal buffering capacity.
Describe the effective pH range of Acetate/CH3COOH buffer.
The effective pH range of Acetate/CH3COOH buffer is 4.76, with a range of 3.6-5.6.
Define the pKa and its significance in buffer selection.
The pKa is the negative logarithm of the acid dissociation constant, and it is significant in buffer selection because a buffer should be chosen whose pKa is close to the desired pH.
How is TRIS buffer prepared using TRIS base and HCl?
TRIS buffer is prepared by dissolving the TRIS base in water and then adjusting the pH with HCl, generating the acid form of TRIS.
Explain the process of preparing TRIS buffer using TRIS hydrochloride.
TRIS buffer can be prepared by combining TRIS base and TRIS hydrochloride in the appropriate ratio.
What is the role of intracellular and extracellular buffer systems in the human body?
The role of intracellular and extracellular buffer systems is to maintain hydrogen ion homeostasis and keep the pH around 7, which is essential for proper cellular function.
Calculate the pH of a buffer solution containing 0.15M acetic acid and 0.25M sodium acetate with a pKa of 4.76.
Using the Henderson-Hasselbalch equation, the pH can be calculated as pH = pKa + log([A-]/[HA]). In this case, pH = 4.76 + log(0.25/0.15).
What is the neutral pH value and its significance?
The neutral pH value is 7, which is significant because it indicates a balance between hydrogen ions and hydroxide ions, making the solution neither acidic nor alkaline.
How does the concentration of H+ relate to pH?
The concentration of H+ is related to pH by the formula pH = -log[H+], meaning that as the concentration of H+ increases, the pH decreases.
Describe the characteristics of acidic and alkaline solutions based on pH.
Acidic solutions have a pH less than 7 (higher [H+]), while alkaline solutions have a pH greater than 7 (lower [H+]).
What happens to H+ ions in the presence of acids and bases?
Acids tend to release H+ ions, while bases tend to accept H+ ions.
List the effective pH range for HEPES buffer.
The effective pH range for HEPES buffer is 7.48, with a range of 6.8-8.2.
Identify the effective pH range for Tris/HCl buffer.
The effective pH range for Tris/HCl buffer is 8.06, with a range of 7.5-9.
What is the effective pH range for the PIPES buffer?
The effective pH range for the PIPES buffer is 6.76, with a range of 6.1-7.5.
How can the pH of a solution be calculated from OH- concentrations?
The pH can be calculated from OH- concentrations using the formula pH = 14 - pOH, where pOH = -log[OH-].
Calculate the H+ concentration for a solution with a pH of 4.3.
The H+ concentration can be calculated using the formula [H+] = 10^(-pH). For pH 4.3, [H+] = 10^(-4.3).
What is the effective pH range for Tricine buffer?
The effective pH range for Tricine buffer is 8.05, with a range of 7.4-8.8.
Describe the effective pH range for NaCO3/NaHCO3 buffer.
The effective pH range for NaCO3/NaHCO3 buffer is 10.33, with a range of 9.0-10.7.
Describe the behavior of strong acids and bases in solution.
Strong acids and bases completely dissociate when they are in solution.
Explain the dissociation of weak acids and bases in solution.
Weak acids and bases are not fully dissociated when they are in solution.
Define a buffer solution.
A buffer is a solution that minimizes the change of the pH when a strong acid or strong base is added to it.
How can a buffer be created?
A buffer can be made by mixing a weak acid and its conjugate base.
What is the significance of pK in a buffer solution?
The pK of a buffer solution is the pH at which the acid (HA) and the base (A-) of the buffer are at equal concentration.
Identify the condition for maximal buffering capacity.
Maximal buffering capacity occurs when the pH equals the pKa.
