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Biological Sciences Foundation Year > Acid, basic and buffer > Flashcards

Acid, basic and buffer Flashcards

1
Q

Describe the role of water in biological systems.

A

Water acts as a solvent inside and outside the cell, facilitating biochemical reactions and the transport of substances.

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2
Q

Define pH and its significance in biological fluids.

A

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.

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3
Q

How is pH calculated from hydrogen ion concentration?

A

pH is calculated using the formula pH = -log

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4
Q

What is the pH of pure water and why is it considered neutral?

A

The pH of pure water is 7, which is considered neutral because it has equal concentrations of hydrogen ions [H+] and hydroxide ions [OH-].

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5
Q

Explain the implications of pH changes in biological systems.

A

Changes in pH to more acidic (pH < 7) or more basic (pH > 7) conditions can disrupt protein shape and function, affecting cellular processes.

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6
Q

Identify the characteristics of acidic and basic solutions based on pH.

A

Acidic solutions have a pH < 7 (high [H+]), while basic solutions have a pH > 7 (low [H+]).

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7
Q

What is the importance of maintaining pH within a specific range in cells?

A

Maintaining pH around 7 is essential for the proper functioning of proteins, which play critical roles as enzymes, transporters, and receptors.

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8
Q

Define acids and provide an example.

A

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).

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9
Q

Define bases and provide an example.

A

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).

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10
Q

What happens to pH when an acid is added to a solution?

A

When an acid is added to a solution, the concentration of H+ increases, causing the pH to decrease.

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11
Q

What happens to pH when a base is added to a solution?

A

When a base is added to a solution, the concentration of H+ decreases, resulting in an increase in pH.

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12
Q

Define the dissociation constant for weak acids and bases.

A

The dissociation constant (Ka) for weak acids and bases is less than 1, indicating that they are mainly undissociated at equilibrium.

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13
Q

How is the pH of a strong basic solution calculated?

A

The pH of a strong basic solution can be calculated using the concentration of hydroxide ions (OH-).

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14
Q

Explain the significance of the Ka value for HCl.

A

A Ka value greater than 1 indicates that HCl is mostly dissociated in solution, leading to a low concentration of undissociated HCl.

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15
Q

What is a buffer solution?

A

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.

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16
Q

How does a buffer maintain pH when acids are added?

A

When acids are added, the H+ ions react with the conjugate base in the buffer, preventing significant changes in pH.

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17
Q

What happens to pH when bases are added to a buffer solution?

A

When bases are added, the OH- ions react with H+ from the weak acid in the buffer, forming water and maintaining the pH.

18
Q

Describe the Henderson-Hasselbalch equation.

A

The Henderson-Hasselbalch equation is pH = pKa + log10[A-]/[HA], used to calculate the pH of a buffer solution.

19
Q

What is the significance of pKa in a buffer solution?

A

The pKa is the pH at which the concentrations of the acid (HA) and its conjugate base (A-) are equal, providing maximal buffering capacity.

20
Q

Describe the effective pH range of Acetate/CH3COOH buffer.

A

The effective pH range of Acetate/CH3COOH buffer is 4.76, with a range of 3.6-5.6.

21
Q

Define the pKa and its significance in buffer selection.

A

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.

22
Q

How is TRIS buffer prepared using TRIS base and HCl?

A

TRIS buffer is prepared by dissolving the TRIS base in water and then adjusting the pH with HCl, generating the acid form of TRIS.

23
Q

Explain the process of preparing TRIS buffer using TRIS hydrochloride.

A

TRIS buffer can be prepared by combining TRIS base and TRIS hydrochloride in the appropriate ratio.

24
Q

What is the role of intracellular and extracellular buffer systems in the human body?

A

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.

25
Q

Calculate the pH of a buffer solution containing 0.15M acetic acid and 0.25M sodium acetate with a pKa of 4.76.

A

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).

26
Q

What is the neutral pH value and its significance?

A

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.

27
Q

How does the concentration of H+ relate to pH?

A

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.

28
Q

Describe the characteristics of acidic and alkaline solutions based on pH.

A

Acidic solutions have a pH less than 7 (higher [H+]), while alkaline solutions have a pH greater than 7 (lower [H+]).

29
Q

What happens to H+ ions in the presence of acids and bases?

A

Acids tend to release H+ ions, while bases tend to accept H+ ions.

30
Q

List the effective pH range for HEPES buffer.

A

The effective pH range for HEPES buffer is 7.48, with a range of 6.8-8.2.

31
Q

Identify the effective pH range for Tris/HCl buffer.

A

The effective pH range for Tris/HCl buffer is 8.06, with a range of 7.5-9.

32
Q

What is the effective pH range for the PIPES buffer?

A

The effective pH range for the PIPES buffer is 6.76, with a range of 6.1-7.5.

33
Q

How can the pH of a solution be calculated from OH- concentrations?

A

The pH can be calculated from OH- concentrations using the formula pH = 14 - pOH, where pOH = -log[OH-].

34
Q

Calculate the H+ concentration for a solution with a pH of 4.3.

A

The H+ concentration can be calculated using the formula [H+] = 10^(-pH). For pH 4.3, [H+] = 10^(-4.3).

35
Q

What is the effective pH range for Tricine buffer?

A

The effective pH range for Tricine buffer is 8.05, with a range of 7.4-8.8.

36
Q

Describe the effective pH range for NaCO3/NaHCO3 buffer.

A

The effective pH range for NaCO3/NaHCO3 buffer is 10.33, with a range of 9.0-10.7.

37
Q

Describe the behavior of strong acids and bases in solution.

A

Strong acids and bases completely dissociate when they are in solution.

38
Q

Explain the dissociation of weak acids and bases in solution.

A

Weak acids and bases are not fully dissociated when they are in solution.

39
Q

Define a buffer solution.

A

A buffer is a solution that minimizes the change of the pH when a strong acid or strong base is added to it.

40
Q

How can a buffer be created?

A

A buffer can be made by mixing a weak acid and its conjugate base.

41
Q

What is the significance of pK in a buffer solution?

A

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.

42
Q

Identify the condition for maximal buffering capacity.

A

Maximal buffering capacity occurs when the pH equals the pKa.

Biological Sciences Foundation Year (17 decks)

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