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pH and pOH quiz #3

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Terms in this set (40)

  • What is the pH of a neutral solution at a temperature when Kw = 1.8 x 10^-14?
    pH = -log(√Kw) = -log(√1.8 x 10^-14) ≈ 6.87
  • What is the pOH of a 0.0085 M KOH solution?
    pOH = -log(0.0085) ≈ 2.07
  • What is the [H3O+] in a solution with [OH–] = 1 x 10^-12 M?
    [H3O+] = Kw / [OH–] = 1 x 10^-14 / 1 x 10^-12 = 1 x 10^-2 M
  • What do pH and pOH add up to at 25 degrees C?
    pH + pOH = 14
  • What is the pH of a 0.1 M Ba(OH)2 aqueous solution?
    Ba(OH)2 gives 2 OH– per unit: [OH–] = 0.2 M, pOH = -log(0.2) ≈ 0.70, pH = 13.30
  • What does pH measure in a solution?
    pH measures the concentration of hydrogen ions (H+).
  • How does the value of pH compare with the concentrations of hydronium ion and hydroxide ion?
    Lower pH means higher [H3O+]; higher pH means higher [OH–].
  • Which of these substances has the highest pOH: lemon juice, milk, ammonia, water?
    Lemon juice has the highest pOH (most acidic).
  • A cup of coffee has a hydroxide ion concentration of 1.0 x 10^-10 M. What is the pH of this coffee?
    [H3O+] = Kw / [OH–] = 1 x 10^-14 / 1 x 10^-10 = 1 x 10^-4 M; pH = 4
  • What is the pH of a 10^-5 M KOH solution?
    pOH = -log(1 x 10^-5) = 5; pH = 14 - 5 = 9
  • Given that the pH of a solution is 6.7, what is its acidity?
    It is weakly acidic.
  • What is a neutral solution?
    A solution with equal concentrations of H+ and OH– ions, typically pH 7 at 25°C.
  • What is the pH of a solution with a hydronium ion concentration of 0.001 M?
    pH = -log(0.001) = 3
  • Which solution below has the highest concentration of hydronium ions: pH 2, pH 5, pH 7, pH 10?
    The solution with pH 2.
  • What is the [OH–] of a solution whose pH = 5.43?
    pOH = 14 - 5.43 = 8.57; [OH–] = 10^-8.57 ≈ 2.69 x 10^-9 M
  • What is the pOH of a solution that has a pH of 2?
    pOH = 14 - 2 = 12
  • What is the pH of a 0.3 M solution of a strong acid?
    pH = -log(0.3) ≈ 0.52
  • What is the pH of a 0.056 M HNO3 solution?
    pH = -log(0.056) ≈ 1.25
  • What is pOH?
    pOH is the negative logarithm of the hydroxide ion concentration.
  • What are pH and pOH?
    pH measures H+ concentration; pOH measures OH– concentration.
  • Which pH value corresponds to the highest hydrogen ion concentration among pH 1, pH 4, pH 7, and pH 10?
    The solution with pH 1.
  • Which of these solutions has the highest concentration of H+?
    The solution with the lowest pH.
  • What is the concentration of hydroxide ion for the solutions with the highest pH that was studied?
    The solution with the highest pH has the highest [OH–] concentration.
  • What is the concentration of H+ in 2.0 M acetic acid?
    Calculate using the Ka and ICE table; for strong acids, [H+] ≈ 2.0 M, but acetic acid is weak.
  • What is the pH of an aqueous solution with [H3O+] = 4 x 10^-13 M?
    pH = -log(4 x 10^-13) ≈ 12.40
  • A solution is classified as a weak base. Which of these could be the pH of the solution: 8, 12, 6, 3?
    A weak base could have a pH around 8.
  • What is the pH of a 2.0 x 10^-4 M HCl solution?
    pH = -log(2.0 x 10^-4) ≈ 3.70
  • Which number represents the pH of a solution with the highest concentration of hydrogen ions: 1, 4, 7, 10?
    pH 1.
  • What happens to the hydrogen-ion concentration as pH increases?
    Hydrogen-ion concentration decreases.
  • What is the pH of a solution that is half as acidic as one that has a pH = 2.40?
    pH increases by 0.30 units (since each pH unit is a tenfold change).
  • Which expresses the relationship of pH to pOH?
    pH + pOH = 14 at 25°C.
  • How do I find the pOH from Kb?
    Calculate [OH–] from Kb and concentration, then pOH = -log[OH–].
  • What is the pH of a solution with [OH–] = 1 x 10^-4 M?
    pOH = 4; pH = 14 - 4 = 10
  • Which pH would indicate the most acidic substance: 1, 4, 7, 10?
    pH 1.
  • Which substance should have the highest pH: NaOH, HCl, CH3COOH, NH4Cl?
    NaOH.
  • Which substance has the highest pH: lemon juice, milk, ammonia, water?
    Ammonia.
  • What is the hydronium ion concentration in a solution of pH 2.27?
    [H3O+] = 10^-2.27 ≈ 5.37 x 10^-3 M
  • What can you use to test the pH of a solution?
    pH paper, pH meter, or indicators.
  • Is an aqueous solution of HCO3– at 25°C acidic?
    It is slightly basic.
  • What is the pH of a solution with a hydroxyl (OH–) ion concentration of 10^-4 M?
    pOH = 4; pH = 10