CH 17: pH and the pH scale
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Questions and Answers

What does the pH scale range from?

  • 1 to 14
  • 2 to 12
  • 0 to 14 (correct)
  • 0 to 15

    • What does a pH value less than 7 indicate?

  • Neutrality
  • Alkalinity
  • Acidity (correct)
  • Purity

    • What is the formula used to calculate the pH of a solution?

  • $pH = -log[OH^-]$
  • $pH = log[OH^-]$
  • $pH = log[H_3O^+]$
  • $pH = -log[H_3O^+]$ (correct)

    • What is the value of the ion product constant for water (Kw) at 25°C?

    <p>1 x 10^-14</p> Signup and view all the answers

    What do the acid dissociation constant (Ka) and base dissociation constant (Kb) quantify?

    <p>The strength of acids and bases</p> Signup and view all the answers

    What is the relationship between the strength of an acid and its Ka value?

    <p>Stronger acids have higher Ka values</p> Signup and view all the answers

    What is the relationship between the strength of a base and its Kb value?

    <p>Stronger bases have higher Kb values</p> Signup and view all the answers

    What is the pH of a 0.1 M solution of HCl (a strong acid)?

    <p>pH = 1</p> Signup and view all the answers

    What is the purpose of the pH scale?

    <p>To specify the acidity or alkalinity of a solution</p> Signup and view all the answers

    How is pH defined in terms of hydronium ion activity?

    <p>pH = -log[H_3O^+]</p> Signup and view all the answers

    What is the equilibrium constant expression (Kc) for the auto-ionisation of water?

    <p>[H3O+][OH-]</p> Signup and view all the answers

    How does a high Ka value for an acid correlate with its strength?

    <p>It signifies a strong acid.</p> Signup and view all the answers

    What is the relationship between the equilibrium constants Ka and Kb for a conjugate acid-base pair?

    <p>Ka x Kb = Kw</p> Signup and view all the answers

    In which pH range would a solution be classified as basic?

    <p>pH &gt; 7</p> Signup and view all the answers

    Why are indicators used in titrations?

    <p>To determine the equivalence point by changing color based on pH</p> Signup and view all the answers

    What does Kw represent in relation to water's auto-ionisation?

    <p>Equilibrium constant</p> Signup and view all the answers

    How are pH calculations different for weak acids compared to strong acids?

    <p>Weak acids require setting up an equilibrium expression using Ka values</p> Signup and view all the answers

    'Deviation from the normal blood pH of 7.4 can indicate health issues.' Which of the following pH ranges would be indicative of potential health problems?

    <p>pH 5.5 - 6.0</p> Signup and view all the answers

    If a solution has a pOH value of 2, what is its hydroxide ion concentration?

    <p>0.01 M</p> Signup and view all the answers

    What does a high Ka value indicate for acids?

    <p>Strong acid that ionizes significantly</p> Signup and view all the answers

    In the Law of Mass Action, what does the equilibrium constant (Kc) express?

    <p>Concentration of products at equilibrium</p> Signup and view all the answers

    For a conjugate acid-base pair, what is the relationship between Ka and Kb?

    <p>Ka × Kb = Kw</p> Signup and view all the answers

    How are pH calculations for weak acids and bases different from strong ones?

    <p>Equilibrium expressions with Ka or Kb are used for weak acids and bases</p> Signup and view all the answers

    What pH range would be classified as acidic based on the pH scale?

    <p>pH &lt; 7</p> Signup and view all the answers

    Why is understanding the pH scale crucial in various fields like medicine and environmental science?

    <p>To assess human health and ecological impacts</p> Signup and view all the answers

    How do indicators contribute to titrations in determining the equivalence point?

    <p>By changing color based on the pH of the solution</p> Signup and view all the answers

    What does a pH value of 3 indicate?

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

    Which ion product constant represents the product of H₃O⁺ and OH⁻ ions in pure water?

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

    What does a pOH value of 11 indicate about a solution?

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

    How are the molar concentration and pH related for strong acids?

    <p>They have a logarithmic relationship</p> Signup and view all the answers

    Which constant quantifies the strength of a base?

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

    If the pH of a solution changes from 6 to 3, how does this impact its acidity?

    <p>It becomes more acidic</p> Signup and view all the answers

    What is the primary factor that determines whether a solution is acidic or basic?

    <p>[H3O+] concentration</p> Signup and view all the answers

    What is the primary factor that determines the acidity or basicity of a solution according to the pH scale?

    <p>The concentration of hydronium ions (H₃O⁺)</p> Signup and view all the answers

    Which of the following is the correct formula to calculate the pH of a solution?

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

    What does the ion product constant for water (Kw) represent at 25°C?

    <p>The product of the molar concentrations of H₃O⁺ and OH⁻ ions in pure water</p> Signup and view all the answers

    How are the acid dissociation constant (Ka) and base dissociation constant (Kb) related for a conjugate acid-base pair?

    <p>Ka and Kb are inversely proportional</p> Signup and view all the answers

    What does a higher Ka value indicate about the strength of an acid?

    <p>The acid is stronger</p> Signup and view all the answers

    What is the pH of a 0.1 M solution of the strong acid HCl?

    <p>pH = 1</p> Signup and view all the answers

    What is the relationship between the strength of a base and its Kb value?

    <p>Stronger bases have higher Kb values</p> Signup and view all the answers

    If the pH of a solution changes from 6 to 3, how does this impact the acidity of the solution?

    <p>The solution becomes more acidic</p> Signup and view all the answers

    What is the relationship between the equilibrium constants Ka and Kb for a conjugate acid-base pair?

    <p>Ka and Kb are inversely proportional</p> Signup and view all the answers

    What does a pH value of 3 indicate about the acidity of a solution?

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

    What is the primary purpose of the equilibrium constant (Kc) in the Law of Mass Action as it applies to chemical reactions?

    <p>To express the relationship between the concentrations of reactants and products at equilibrium</p> Signup and view all the answers

    How do the Ka and Kb values of a conjugate acid-base pair relate to each other?

    <p>The product of Ka and Kb is equal to the equilibrium constant (Kc)</p> Signup and view all the answers

    Which of the following best describes the relationship between the pH of a solution and the concentration of hydronium ions (HO)?

    <p>pH is inversely proportional to the concentration of HO ions</p> Signup and view all the answers

    How do the Ka and Kb values of an acid and its conjugate base relate to their relative strengths?

    <p>A high Ka value indicates a strong acid, while a high Kb value indicates a strong base</p> Signup and view all the answers

    What is the significance of the ion product constant (Kw) for water's auto-ionisation?

    <p>Kw represents the equilibrium constant for the dissociation of water into hydronium and hydroxide ions</p> Signup and view all the answers

    Why are indicators used in titrations to determine the equivalence point?

    <p>Indicators change color based on the pH of the solution, allowing the equivalence point to be identified</p> Signup and view all the answers

    How do the pH calculations differ between strong acids/bases and weak acids/bases?

    <p>For strong acids/bases, the pH calculation is straightforward, but for weak acids/bases it involves setting up an equilibrium expression using Ka or Kb</p> Signup and view all the answers

    What is the relationship between the pH of a solution and its acidity?

    <p>As the pH of a solution decreases, its acidity increases</p> Signup and view all the answers

    How does the pH of natural water bodies and biological fluids impact their health and functioning?

    <p>The pH of natural water bodies and biological fluids is crucial for the health of ecosystems and organisms, as deviations from the optimal range can lead to adverse effects</p> Signup and view all the answers

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