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pH and pOH quiz #5

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Terms in this set (40)

  • What is the pH after the addition of 5.0 mL of HCl to ethylamine?
    Calculate moles of HCl and ethylamine, determine excess, then calculate pH.
  • A solution has a [H3O+] = 6.0 x 10^-5 M at 25°C. What is the [OH–] of the solution?
    [OH–] = Kw / [H3O+] = 1 x 10^-14 / 6 x 10^-5 ≈ 1.67 x 10^-10 M
  • What is the pH of 0.048 M solution of hydrochloric acid?
    pH = -log(0.048) ≈ 1.32
  • What is the pH indicator in the citrate test?
    Bromothymol blue.
  • What is the pH of a 0.25 M solution of KHCOO? Ka (HCOOH) = 1.8 x 10^-4
    Calculate using hydrolysis of HCOO–; solution is basic.
  • What is the pH of a solution made by diluting 25 mL of 6.0 M HCl(aq) to a total volume of 0.200 L?
    Final [HCl] = (25 mL x 6.0 M) / 200 mL = 0.75 M; pH = -log(0.75) ≈ 0.12
  • What is the pOH of a 100 mL solution of 0.7 M HL? Round your answer to two places past the decimal.
    Calculate pH from [H+], then pOH = 14 - pH.
  • What is the pH of a 0.570 M solution of aniline (C6H5NH2)? Kb = 7.4 x 10^-10
    Use Kb and ICE table to solve for [OH–], then pOH and pH.
  • What is the pH of a 7.5 x 10^-3 M Ba(OH)2 solution at 25°C?
    [OH–] = 2 x 7.5 x 10^-3 = 0.015 M; pOH = -log(0.015) ≈ 1.82; pH = 12.18
  • What is used to adjust the pH of a compound?
    Acids or bases.
  • What is the pH of a 0.470 M solution of pyridine (C5H5N)? Kb = 1.5 x 10^-9
    Use Kb and ICE table to solve for [OH–], then pOH and pH.
  • What is the pH of a 0.350 M MgF2 solution? Ka of HF = 3.5 x 10^-4
    Calculate using hydrolysis of F–; solution is basic.
  • What is the pH of a solution of 0.25 M K3PO4?
    Calculate using hydrolysis of PO4^3–; solution is basic.
  • Suppose that a 25°C solution has a pOH of 8.6. What is the concentration of hydronium ions?
    pH = 14 - 8.6 = 5.4; [H3O+] = 10^-5.4 ≈ 4.0 x 10^-6 M
  • What is the pH of a 0.0000100 M solution of CsOH?
    pOH = -log(1 x 10^-5) = 5; pH = 9
  • The H+ concentration in an aqueous solution at 25°C is 4.3 x 10^-8 M. What is [OH–]?
    [OH–] = Kw / [H+] = 1 x 10^-14 / 4.3 x 10^-8 ≈ 2.33 x 10^-7 M
  • What is the pH of a 2.5 x 10^-8 M CsOH solution?
    pOH = -log(2.5 x 10^-8) ≈ 7.60; pH = 6.40
  • What is the hydronium ion concentration of a solution whose pH is 10.34?
    [H3O+] = 10^-10.34 ≈ 4.57 x 10^-11 M
  • Calculate [OH–] in a solution that has [H3O+] = 6.7 x 10^-2 M. Is the solution acidic or basic?
    [OH–] = Kw / [H3O+] = 1 x 10^-14 / 6.7 x 10^-2 ≈ 1.49 x 10^-13 M; solution is acidic.
  • What is the pH of a 2.4 M solution of HClO4?
    pH = -log(2.4) ≈ -0.38
  • What is the pH of a mixture of 15 mL of 0.25 M HC2H3O2 and 0.46 g of NaC2H3O2·3H2O?
    Calculate moles, set up buffer equation, use Henderson-Hasselbalch.
  • What is the pH of a 1.2 M ammonia solution? Give your answer to two decimal places.
    Use Kb and ICE table for NH3; pH ≈ 11.22
  • Suppose that a 25°C solution has a pOH of 8.60. What is the concentration of hydronium ions?
    pH = 14 - 8.60 = 5.40; [H3O+] = 10^-5.40 ≈ 4.0 x 10^-6 M
  • What is the pOH of a solution at 25.0°C with [OH–]=2.7 x 10^-2 M?
    pOH = -log(2.7 x 10^-2) ≈ 1.57
  • The pH of a 0.050 M aqueous solution of ammonium chloride (NH4Cl) falls within what range?
    NH4Cl is slightly acidic; pH is less than 7.
  • What is the pH of a 0.300 M solution of aniline (C6H5NH2)?
    Use Kb and ICE table for weak base.
  • The pOH of a solution is 9.70. What is the H+ concentration in the solution?
    pH = 14 - 9.70 = 4.30; [H+] = 10^-4.30 ≈ 5.01 x 10^-5 M
  • A 1.25 M solution of the weak acid HA is 9.2% dissociated. What is the pH of the solution?
    [H+] = 1.25 x 0.092 = 0.115 M; pH = -log(0.115) ≈ 0.94
  • What is the pOH if a solution composed of 60 mL of 0.0012 M HCl and 200 mL of 0.0005 M NaOH?
    Calculate moles, find excess, determine [OH–], then pOH.
  • What is the [OH–] in a solution that has a pOH of 9.65?
    [OH–] = 10^-9.65 ≈ 2.24 x 10^-10 M
  • You determine the pH of an energy drink is 4.33. What is the hydronium ion concentration?
    [H3O+] = 10^-4.33 ≈ 4.68 x 10^-5 M
  • The pH of a solution is 3.45. What is the OH– concentration in the solution?
    pOH = 14 - 3.45 = 10.55; [OH–] = 10^-10.55 ≈ 2.82 x 10^-11 M
  • What is the pH of a 0.135 M NaCN solution? Ka of HCN = 4.9 x 10^-10
    Calculate using hydrolysis of CN–; solution is basic.
  • What is the pH of a solution with [H3O+]=8.2 x 10^-3 M?
    pH = -log(8.2 x 10^-3) ≈ 2.09
  • What is the approximate hydrogen ion concentration for stomach acid with a pH of 2.7?
    [H+] = 10^-2.7 ≈ 2.0 x 10^-3 M
  • What is the pH of a neutral solution at a temperature when Kw = 2.2 x 10^-14?
    pH = -log(√2.2 x 10^-14) ≈ 6.77
  • Which type of solution exhibits the greatest change in pH when 1.0 mL of 1 M HCl is added: pure water, buffer, strong base, or weak acid?
    Pure water.
  • What does pH measure?
    The concentration of hydrogen ions (H+) in a solution.
  • Which would most likely be the pH of a highly-corrosive acid: 1, 5, 8, 11?
    pH 1.
  • Which of these correctly defines the pOH of a solution?
    pOH is the negative logarithm of the hydroxide ion concentration.