Biochemistry Chapter: Buffer Systems and Properties
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Questions and Answers

What is the primary role of the phosphate buffer system?

  • To maintain pH in intracellular fluid and renal tubules (correct)
  • To transport oxygen in the blood
  • To assist in the exhalation of carbon dioxide
  • To neutralize fixed acids in the bloodstream

    • What pH value does the phosphate buffer function most effectively at?

  • 6.8 (correct)
  • 7.4
  • 7.0
  • 4.5

    • Which group in amino acids helps neutralize acids when they enter the blood?

  • -NH2 groups
  • -COOH groups
  • -NH3+ groups
  • -COO- groups (correct)

    • What occurs during hyperventilation in relation to blood pH?

    <p>pH increases as H+ ions are removed</p> Signup and view all the answers

    What does the presence of dissolved substances do to the structure of liquid water?

    <p>It disturbs the structure and creates local order.</p> Signup and view all the answers

    Which of the following is NOT a colligative property of water?

    <p>Density change</p> Signup and view all the answers

    Which physiologic buffer system is most effective in regulating pH?

    <p>Renal regulation</p> Signup and view all the answers

    What happens to the pH during hypoventilation?

    <p>pH decreases due to increased H+ concentration</p> Signup and view all the answers

    How does freezing point depression relate to the presence of solutes in water?

    <p>Solutes make it more difficult for water to freeze.</p> Signup and view all the answers

    What is vapor pressure in the context of water?

    <p>The pressure at which the liquid and gas phases are in equilibrium.</p> Signup and view all the answers

    Which of the following is NOT a function of hemoglobin related to pH balance?

    <p>Neutralizing fixed acids</p> Signup and view all the answers

    What effect do nonpolar solutes have on water molecules in terms of entropy?

    <p>They promote a net decrease in order of water molecules.</p> Signup and view all the answers

    How do cells minimize osmotic pressure related to their cytosol?

    <p>By storing substances like sugars in polymeric form.</p> Signup and view all the answers

    What is one consequence of increasing solute concentration in water regarding boiling point?

    <p>Boiling point increases.</p> Signup and view all the answers

    What is the osmotic pressure of a solution influenced by?

    <p>The solute concentration in the solution.</p> Signup and view all the answers

    According to the Arrhenius definition, what do acids produce in water?

    <p>H+ ions</p> Signup and view all the answers

    What is the role of water when HCl reacts according to the Brønsted-Lowry definition?

    <p>It acts as a base.</p> Signup and view all the answers

    In the reaction HCl + H2O ⇌ Cl- + H3O+, what is Cl- identified as?

    <p>Conjugate base</p> Signup and view all the answers

    What characterizes a Brønsted-Lowry acid?

    <p>It donates a proton.</p> Signup and view all the answers

    Which of the following substances acts as a Brønsted-Lowry base in the reaction NH3 + H2O ⇌ NH4+ + OH-?

    <p>NH3</p> Signup and view all the answers

    What is the correct definition of a conjugate base?

    <p>The substance that remains after an acid donates a proton.</p> Signup and view all the answers

    Which statement about the Arrhenius and Brønsted-Lowry definitions is true?

    <p>Brønsted-Lowry theory allows for reactions outside of water.</p> Signup and view all the answers

    When HCl donates a proton to water, what is formed besides the conjugate base?

    <p>Hydronium ion</p> Signup and view all the answers

    What is formed when a base accepts a proton according to the Brønsted-Lowry definition?

    <p>A conjugate acid</p> Signup and view all the answers

    What is the pH of a neutral solution at 25°C?

    <p>7</p> Signup and view all the answers

    Which of the following statements is true about the ionization constant of water (Kw)?

    <p>Kw increases with an increase in temperature.</p> Signup and view all the answers

    What is the relationship between pH and pOH in any aqueous solution?

    <p>pH + pOH = 14</p> Signup and view all the answers

    In pure water, what is the relationship between [H+] and [OH-]?

    <p>[H+] is equal to [OH-]</p> Signup and view all the answers

    Which property is characteristic of an acid?

    <p>Reacts with metals to produce H2</p> Signup and view all the answers

    What does a pH of less than 7 indicate about a solution?

    <p>The solution is acidic.</p> Signup and view all the answers

    Which equation represents the ionization of water?

    <p>H2O (l) ↔ H+ (aq) + OH- (aq)</p> Signup and view all the answers

    What is the product of the concentrations of hydrogen ions and hydroxide ions in pure water at 25°C?

    <p>1.0 x 10-14</p> Signup and view all the answers

    What would happen to the pH of water if the temperature increases significantly?

    <p>pH decreases.</p> Signup and view all the answers

    What happens when an acid reacts with a base?

    <p>A salt and water are produced.</p> Signup and view all the answers

    Which of the following statements accurately describes strong acids?

    <p>Strong acids completely dissociate into their ions when mixed with water.</p> Signup and view all the answers

    Identify the correct conjugate acid-base pair from the reaction HCl + OH ̶ → Cl ̶ + H2O.

    <p>HCl and Cl ̶</p> Signup and view all the answers

    Given a solution with a pH of 3.17, what is the [H3O+] concentration?

    <p>$4.79 imes 10^{-4} ext{ M}$</p> Signup and view all the answers

    Which statement about weak acids is true?

    <p>Weak acids create an equilibrium in their dissociation.</p> Signup and view all the answers

    What is the general behavior of strong bases in aqueous solutions?

    <p>They completely dissociate into their ions.</p> Signup and view all the answers

    How do you calculate the pH from hydronium ion concentration?

    <p>pH = -log [H3O+]</p> Signup and view all the answers

    If a solution has a pH of 8.5, what is the molarity of hydrogen ions in the solution?

    <p>$1.12 imes 10^{-6} ext{ M}$</p> Signup and view all the answers

    In the reaction H2O + H2SO4 → HSO4 ̶ + H3O+, which species is acting as the Brønsted-Lowry acid?

    <p>H2SO4</p> Signup and view all the answers

    Study Notes

    Chapter 2: Water: The Medium of Life

    • Life originated, evolved, and thrives in the seas.
    • Water and its ionization products, hydrogen ions and hydroxide ions, are critical determinants of the structure and function of many biomolecules.
    • A difference in the concentration of hydrogen ions on opposite sides of a membrane represents an energized condition essential to biological mechanisms of energy transformation.
    • Water has a substantially higher boiling point, melting point, heat of vaporization, and surface tension.
    • Water's maximum density is found in the liquid state.
    • Permanent dipoles occur when two atoms in a molecule have substantially different electronegativity. One atom attracts electrons more than another, becoming more negative, while the other atom becomes more positive.
    • Hydrogen bonding in water is key to its properties.
    • The solvent properties of water derive from its polar nature.
    • The solvent properties of water derive from its polar nature.
    • The solvent properties of water derive from its polar nature.

    Outline

    • 2.1 What are the properties of water?
    • 2.2 What is pH?
    • 2.3 What are buffers and what do they do?
    • 2.4 What properties of water give it a unique role in the environment?

    Colligative Properties

    • The presence of dissolved substances disturbs the structure of liquid water, changing its properties.
    • The net effect is that solutes fix nearby water molecules in a more ordered array.
    • The influence of the solute on water is reflected in characteristic changes in behavior termed colligative properties.
    • These properties include freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure effects.

    Auto-ionization of Water

    • Water undergoes self-ionization, producing hydronium ions (H₃O⁺) and hydroxide ions (OH⁻).
    • In pure water, the concentration of hydronium ions ([H₃O⁺]) is equal to the concentration of hydroxide ions ([OH⁻]).

    What is pH?

    • An aqueous solution is neutral when [H⁺] = [OH⁻].
    • An aqueous solution is acidic when [H⁺] > [OH⁻].
    • An aqueous solution is basic when [H⁺] < [OH⁻].
    • pH = -log[H⁺] or pH = -log[H₃O⁺]

    pH Scale

    • The pH scale is used to measure the acidity or basicity of a solution.
    • The pH scale ranges from 0 to 14.
    • A pH of 7 is neutral.
    • A pH less than 7 is acidic.
    • A pH greater than 7 is basic.

    pH Calculation

    • pH is calculated using the formula pH = -log[H⁺]
    • pOH is calculated using the formula pOH = -log[OH⁻]
    • pH + pOH = 14

    Strong vs Weak Acids

    • Strong acids ionize 100% in water.
    • Weak acids have incomplete dissociation in water.

    Common Strong Acids and Bases

    • A list of common strong acids and bases is provided

    Buffering of a Chemical System

    • Buffers are systems that resist large fluctuations in pH.
    • Buffers consist of a weak acid and its conjugate base, or a weak base and its conjugate acid.
    • Buffers work by absorbing excess hydrogen or hydroxide ions.
    • Examples of buffer systems include the bicarbonate buffer system and the phosphate buffer system.

    Physiological Buffers

    • The lungs excrete CO₂ to maintain pH balance.
    • The kidneys excrete H⁺ and conserve HCO₃⁻ to maintain pH balance.

    Bicarbonate Buffer System

    • The bicarbonate buffer system is crucial for maintaining blood pH.
    • The carbonic acid-bicarbonate buffer system plays a significant role in acid-base balance.

    Renal Bicarbonate Regeneration

    • The kidneys play a vital role in regenerating bicarbonate after it's been filtered.
    • It involves an enzyme, carbonate dehydratase.

    Regulation of Plasma pH- Acidosis and Alkalosis

    • The body's pH is regulated by a combination of respiratory and renal processes.
    • Respiratory processes primarily regulate the carbonic acid-bicarbonate buffer system.
    • The renal processes regulate the excretion of hydrogen and bicarbonate ions.

    Acids and Bases

    • In the early days of chemistry, certain properties of compounds were categorized.
    • Acids have certain properties (such as sour taste)
    • Bases have certain properties (such as bitter taste)
    • Arrhenius proposed the concept of Acids and Bases.
    • Acids dissociate in water to produce H+ ions.
    • Bases dissociate in water to produce OH- ions.
    • Brønsted-Lowry revised the Arrhenius definition to include other solvents.
    • An acid is a proton donor.
    • A base is a proton acceptor.
    • Strong acids fully dissociate in water.
    • Weak acids only partially dissociate in water
    • Strong bases fully dissociate in water.
    • Weak bases only partially dissociate in water.

    Reactions of Acids and Bases.

    • Acids react with metals generating hydrogen gas.
    • Acids react with carbonates and bicarbonates generating carbon dioxide gas.
    • Acids react with hydroxides generating water and salt compounds. (Neutralization reactions)

    Other Important Concepts

    • The concept of conjugate pairs and how they are formed as a result of acid or base reactions.
    • The role of various compounds as buffers and their importance in maintaining pH levels in the body.
    • The concept of the limitations of the buffer system.
    • The importance of maintaining, and regulating body pH.

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    Chapter 2: Water: The Medium of Life PDF

    Description

    Test your understanding of buffer systems, particularly the phosphate buffer system, and their physiological roles. This quiz covers pH regulation, colligative properties of water, and the effects of solutes on water structure. Dive into the intricate relationships between solutes and water properties to strengthen your biochemistry knowledge.

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