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pH and pOH quiz #2

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Terms in this set (39)

  • What is the pH of an HCl solution if [H+] = 0.03 M?
    pH = -log(0.03) ≈ 1.52
  • What is the pH of the solution at the equivalence point in a strong acid-strong base titration?
    The pH is approximately 7.
  • Seawater has a pH of 8.1. What is the concentration of OH–?
    [OH–] = 10^-(14 - 8.1) ≈ 1.26 x 10^-6 M
  • What tool can we use to get accurate information about the pH of a substance?
    A pH meter.
  • A solution has a [OH–] = 1.8 x 10^-10 M at 25°C. What is the [H3O+] of the solution?
    [H3O+] = Kw / [OH–] = 1.0 x 10^-14 / 1.8 x 10^-10 ≈ 5.56 x 10^-5 M
  • A solution's pH is a measure of what?
    The concentration of hydrogen ions (H+) in the solution.
  • What is the pH of orange juice?
    Orange juice typically has a pH around 3-4.
  • Which pH value corresponds to the highest proton concentration among pH 2, pH 5, pH 7, and pH 10?
    The solution with pH 2.
  • What is the pH of a 0.808 M KOBR solution if the Ka of HOBR is 2.0 x 10^-9?
    Since KOBR is a salt of a weak acid and strong base, the solution is basic. Calculate pOH using hydrolysis, then pH = 14 - pOH.
  • Is it ever possible to have a strong acid with a pH that is higher than a weak acid?
    No, strong acids always have lower pH than weak acids at the same concentration.
  • Which value for pOH corresponds to an acidic solution at room temperature?
    pOH less than 7 corresponds to a basic solution; pOH greater than 7 is acidic.
  • What is the pH of a 0.050 M LiOH solution?
    LiOH is a strong base: [OH–] = 0.050 M, pOH = -log(0.050) ≈ 1.30, pH = 14 - 1.30 = 12.70
  • What is the pH of a 10^-7 molar NaOH solution?
    pOH = -log(1 x 10^-7) = 7, pH = 14 - 7 = 7
  • Which of these pH values indicates the highest amount of protons donated: pH 2, pH 5, pH 7, pH 10?
    pH 2 indicates the highest amount of protons.
  • How does the pH of a solution change as the hydrogen ion concentration increases?
    As H+ concentration increases, pH decreases.
  • What is the pH of a 0.250 M solution of KOH?
    KOH is a strong base: [OH–] = 0.250 M, pOH = -log(0.250) ≈ 0.60, pH = 14 - 0.60 = 13.40
  • A solution has a pH of 7.0. What would happen to the pH if H+ ions were added?
    The pH would decrease.
  • The pH of a solution is 9.0. What is its [H3O+] concentration?
    [H3O+] = 10^-9.0 = 1 x 10^-9 M
  • What is the hydroxide ion concentration of a solution whose pH is 12.40?
    pOH = 14 - 12.40 = 1.60; [OH–] = 10^-1.60 ≈ 0.025 M
  • Which substance would have a pH close to 7: pure water, lemon juice, ammonia, vinegar?
    Pure water.
  • What is the relationship between pH and pOH?
    pH + pOH = 14 at 25°C.
  • What pH does distilled water have?
    Distilled water has a pH of 7 at 25°C.
  • What is the pH range of an acid?
    Acids have a pH less than 7.
  • What is the pH of a 0.0500 M solution of Ba(OH)2?
    Ba(OH)2 provides 2 OH– per formula unit: [OH–] = 0.100 M, pOH = -log(0.100) = 1, pH = 13
  • What is the neutral pH?
    Neutral pH is 7 at 25°C.
  • How are pH and pOH related?
    pH + pOH = 14 at 25°C.
  • If a pH indicator turns blue when added to a substance, what does this indicate?
    The substance is basic.
  • What happens to the pH of soda water as it loses its carbonation?
    The pH increases as CO2 escapes.
  • What is the change in pH when the hydrogen ion concentration decreases by a factor of 100?
    The pH increases by 2 units.
  • A solution has a pH of 7.6. What does that say about the solution?
    The solution is slightly basic.
  • What is the pH of a 0.20 M HCl solution?
    pH = -log(0.20) ≈ 0.70
  • What makes pure water neutral?
    Equal concentrations of H+ and OH– ions.
  • What is the pH of an aqueous solution with [H3O+] = 6 x 10^-12 M?
    pH = -log(6 x 10^-12) ≈ 11.22
  • Which of these solutions is the most basic: pH 2, pH 7, pH 10, pH 13?
    pH 13 is the most basic.
  • The pOH of a basic solution is 6.29. What is [H+]?
    pH = 14 - 6.29 = 7.71; [H+] = 10^-7.71 ≈ 1.95 x 10^-8 M
  • What is the pH of a 0.020 M HClO4 solution?
    pH = -log(0.020) ≈ 1.70
  • What is the pH of pure water at 50°C?
    At 50°C, Kw is higher, so pH is less than 7 (exact value depends on Kw at 50°C).
  • What is the pH of a 0.000100 M solution of HBr?
    pH = -log(1 x 10^-4) = 4
  • What is the pH of a 0.040 M Ba(OH)2 solution?
    Ba(OH)2 gives 2 OH– per unit: [OH–] = 0.080 M, pOH = -log(0.080) ≈ 1.10, pH = 12.90