AP Chem Chapter 13: Acid-Base Equilibria

Acid-Base Definitions

  1. Properties

Acids / Bases
Tastes / Tastes
Feels like / Feels
pH / pH
Conducts / Conducts
  1. Three ways to define A-B
  2. Arrhenius – focused on what it ______into
  3. Bronsted-Lowry – focused on ______(_____)
  4. Lewis – Focused on ______(more on this later)
  5. Acids: lone pair ______

Ex: HF(aq) + H2O(l) ⇆ H3O+(aq) + F-(aq)

  1. Bases: lone pair ______

Ex: NH3(aq) +H2O(l) ⇆ NH4+(aq) + OH- (aq)

Acid / Base
Arrhenius
Bronsted-Lowry
Lewis
  1. Water: ______, pH=______, can act as an ______or ______(______or ______)

III. Conjugate acids and bases:

  1. A pair of compounds that differ by a ______(H+)
  2. They are always located on the ______side.
  3. An acid donates an H+ to become its conjugate base.

HCl(aq) → H+(aq) + Cl-(aq)

  1. A base accepts an H+ to become its conjugate acid.

NH3(aq) + H+(aq) ⇆ NH4+(aq)

  1. Label:
  1. NH3(aq) + H2O(l) ⇆ NH4+(aq) + OH-(aq)
  2. HF(aq) + H2O(l) ⇆ H3O+(aq) + F-(aq)

Acid-Base Strength

  1. First, the acid dissociation constant, _____(_____ for bases)
  2. Measures the degree in which acids ______.
  3. It is the ______for an acid dissociating.
  4. Write the acid dissociation constant expression for:
  5. HC2H3O2(aq) ⇆ H+(aq) + C2H3O2-(aq)
  6. NH3(aq) + H+(aq) ⇆ NH4+(aq)
  7. HF(aq) + H2O(l) ⇆ H3O+(aq) + F-(aq)
  8. The ______the Ka or Kb, the more ______, the ______the acid/base.
  1. Strong acids and bases dissociate completely
  2. ~100% ______, therefore strong ______
  3. Acids: ______
  4. Bases: ______(consistent with the solubility rules!)
  1. Weak acids and bases ______dissociate completely
  2. ~1% ______, therefore weak ______
  3. Weak acids: ______that starts with an H
  4. Weak bases: ______
  5. Comparing acid/base strength to conjugate acids/bases
  6. ______acids/bases have ______conjugate acids/bases.
  7. ______acids/bases have ______conjugate acids/bases.

  1. Measuring acid/base strength
  2. Measured using pH and pOH
  3. pH =
  4. pOH =
  5. [H3O+] = [H+] =
  6. [OH-] =
  7. Sig. figs with logs.

a)  When taking the antilog of a quantity, ______.

b)  When taking the log of a quantity, ______.

  1. The autoionization of water:
  2. ______or ______
  3. The equilibrium conc. of H+ and OH- is ______M because ______when pH=______
  4. Kc=Kw=
  5. Kw=(1.00x10-7M)(1.00x10-7M) =
  6. −log Kw = −log [H+] + −log [OH−] =
  7. Therefore, pKw = pH + pOH =
  8. pH depends on ______AND ______.
  9. A weak acid can have a higher pH than a strong acid if the weak acid is much ______than the strong acid.
  1. Calculating pH or pOH
  2. To find the [H+] or [OH-]:
  3. Strong acids-bases: because they dissociate 100%, [acid] or [base] = [ ] or [ ], respectively
  1. Ex: [HCl] = 0.1M =
  2. pH = -log(0.1M) =
  3. What is the pH of a solution prepared by dissolving 1.00g of barium hydroxide into 1 L of water?
  4. Weak acids and bases do not dissociate completely, therefore the ______method will be used
  5. The ______and the ______will be required
  6. If pH or pOH is given, [ ] or [ ] can be found
  7. pKa = ______and pKb = ______
  8. Examples...
  9. To calculate percent dissociation:
  1. Find [H+] or [OH-], ______by original conc. then ______by 100%
  2. % diss. =
  1. Always “keep your head in the beaker.”
  2. A shortcut!!!
  3. Many times, the value of x is very ______.
  4. If this is true, when sig figs are taken into account, the ______of a reactant will be very similar to what it was ______.
  5. Thus, when solving for x using the constant expression, you can assume that the “+x” and the “-x” are zero, making it easier to solve algebraically.
  6. This assumption is good ONLY IF
  7. If the quotient is greater than 5%, use solver.
  1. Polyprotic Acids:
  2. Acids that have ______
  3. Monoprotic acid and dissociation:
    HCl(aq) → H+(aq) + Cl-(aq) Ka
  4. Diprotic acid and dissociation:
    H2SO4(aq) → H+(aq) + HSO4-(aq) Ka1

HSO4-(aq) ⇆ H+(aq) + SO42-(aq) Ka2

  1. Triprotic acid and dissociation:

H3PO4(aq) ⇆ H+(aq) + H2PO4-(aq) Ka1

H2PO4-(aq) ⇆ H+(aq) + HPO42-(aq) Ka2

HPO42-(aq) ⇆ H+(aq) + PO43-(aq) Ka3

  1. ______> ______
  2. Ka or Kb of total reaction = the ______of the Ka’s or Kb’s of each reaction.
  3. Ex. ______for a triprotic acid.

Acid-Base Property of Salts

  1. Salts, when dissolved in ______, can create ______solutions.
  2. Salts of weak acids dissolve to form its ______(ex. sodium acetate).
  3. NaC2H3O2(aq) → Na+(aq) + C2H3O2-(aq)
  4. But there’s water in solution!
  5. Don’t worry about the sodium ion because it is the ______of a ______so it’s not going to react to form the strong base (because it dissociates 100%)
  6. This is also happening, therefore a basic solution is formed!
  1. Salts of weak bases dissolve to form its ______(ex. ammonium chloride).
  2. NH4Cl(aq) → NH4+(aq) + Cl-(aq)
  3. Don’t worry about the chloride ion because it is the conjugate base of a strong acid so it’s not going to react to form the strong acid (because it dissociates 100%)
  4. This is also happening, therefore an acidic solution is formed!

Calculating with Salts

  1. Back to water again...
  2. Kw =
  3. Ka = and Kb =
  4. If Ka is given and you have to ______the reaction, you will need to solve for ______using the above equation and vice versa.
  5. This is valid only for ______.
  6. Examples:
  7. What is the pH of a 0.140M solution of sodium acetate?
  8. What is the pH of a 0.140M solution of diethyl amino chloride?
  9. Predicting pH for a solution that has both acidic and basic properties.
  10. If Ka > Kb , pH 7 (acidic)
  11. If Kb > Ka , pH 7 (basic)
  12. If Ka = Kb , pH 7 (neutral)
  13. Predict whether an aqueous solution of each of the following salts will be basic, acidic, or neutral
  14. NH4C2H3O2
  15. NH4CN
  16. Al2(SO4)3

Structure Effects on Acidity/Basicity

  1. Acid Halides (______)
  2. Acidity depends on a substance’s ability to ______(H+).
  3. If bond strength is ______, proton is ______to dissociate, making it a ______acid.
  4. If bond strength is ______, proton is ______to dissociate, making it a ______acid.
  5. Oxoacids
  6. Oxygen is very ______.
  7. The ______there are, the more they will attract ______away from the ______. This makes the proton dissociate more ______, resulting in a ______acid.
  8. All things being equal, the ______O’s there are, the ______it is.
  9. Example: chlorines...

Reaction Prediction Review

  1. Soluble metal oxides + water -->
  1. Nonmetal oxides + water -->

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