Equilibrium Expressions
Le Chatelier's Principle
Acid/Base Basic Terms
Acids and Bases 1
Acids and Bases 2
100
What is the state of dynamic equilibrium and what is equilibrium constant?
  • The rate of forward reaction and the rate of reverse reaction are equal and there is no net change in the composition.
  • The equilibrium constant is equal to ratio of forward rate constant over reverse rate constant and is equal to the concentrations of the products (raised to powers equal to their stoichiometric coefficients in the balanced chemical reaction) divided by the concentrations of reactants (raised to powers equal to their stoichiometric coefficients in the balanced chemical reaction)
    • 100
    Sum up Le Chatelier's Principle.
    If a system at equilibrium is disturbed by the change in temperature, pressure, or component concentration, the system will shift to minimize the effect of this stress.
    100
  • What is a Bronsted-Lowry Acid?
  • What is a Bronsted-Lowry base?
  • A proton donor
  • A proton acceptor
    • 100
    1. Write the chemical formula for the conjugate acid of the base pyridine C5H5N5
    2. Write the formula for the conjugate base of the acid HIO3.
    1. C5H5N5H+
    2. IO3-
    100
    Decide whether aqueous solutions of the salts:
    1. Na2CO3
    2. AlCl3
    3. KNO3
    are acidic, neutral or basic
    1. basic
    2. acidic
    3. neutral
    200
    1. If Q > K, which way does the reaction go?
    2. If Q < K, which way does the reaction go?
    1. towards reactants, so left
    2. towards products, so right
    200
  • For an endothermic reaction, how does Keq change with decreasing temperature?
  • For an exothermic reaction, how does Keq change with decreasing temperature?
  • As temperature decreases, the equilibrium shifts to the left (reactants side), so Keq will decrease.
  • As temperature decreases, the equilibrium shifts to the right (products side), so Keq will increase.
    • 200
    What is an amphiprotic species? Give a general or specific example.
    Species that can act as acid or base. Examples include partially deprotonated polyprotic acids such as HS-
    200
    Select the stronger acid or base in the following pairs:
    1. HF (pKa = 3.45) or HIO (pKa = 10.64)
    2. C6H5NH2(pKb = 9.37) or (CH3)3N (pKb = 4.19)
    1. HF
    2. (CH3)3N
    200
    List the following carboxylic acids in order of increasing strength: CHCl2COOH, CCl3COOH, CH3COOH, CH2ClCOOH.
    CH3COOH < CH2ClCOOH < CHCl2COOH < CCl3COOH
    300
    Give the expression of equilibrium constant for the following reaction:
  • 2 Ag (s) + Zn(NO3)2 (aq) <--> 2 AgNO3 (aq) + Zn(s)
    • K = [Ag+]2/[Zn2+]
    300
    Adding a catalyst effects each of the following how (increase, decrease, no change)?
    1. rate of kf
    2. rate of kr
    3. Keq
    4. equilibrium shifts
    1. increase
    2. increase
    3. no change
    4. no change
    300
  • What is the pOH if [H+] = 10-5?
  • What is the relationship between pH and pOH?
  • pH = 5, pOH = 9
  • pH + pOH = 14
    • 300
    For each of the following pairs, predict and explain which acid is stronger:
    1. H2S and HCl
    2. HBrO2 and HBrO3
    3. H2SO3 and H2SeO3
    1. HCl (Cl is more electronegative than S)
    2. HBrO3 (greater number of O atoms)
    3. H2SO3 (S is more electronegative then Se)
    300
    What is the percentage deprotonation of acetic acid, CH3COOH, when the [H3O+]= 1.2 x 10-3M. The initial concentration of the acid is 0.10 M.
    1.2 %
    400
    Consider the following equilibrium, for which the Kp = 16:
  • 2 Cl2 (g) + 2 H2O (g) <---> 4 HCl (g) + O2 (g)
    • What is the value of Kp for the reaction:
  • HCl (g) + 1/4 O2(g) <---> 1/2 Cl2 (g) + 1/2 H2O (g)
    • Kp = 1/2 or 0.5
    400
    For the reaction, PbCl2 <-> Pb2+ + 2Cl-, adding AgNO3 does what to the system and why? What does the addition of water do to the system and why?
  • shifts the equilibrium right, because AgCl precipitates, so the Cl- ions are being removed from the solution.
  • shifts the equilibrium right, because addition of water decreases the concentrations of [Pb2+] and [Cl-]
    • 400
    Name 6 of the 7 strong acids.
    HCl, HBr, HI, HNO3, HClO3, HClO4, first dissociation of H2SO4
    400
    For each of the following pairs, predict and explain which base is stronger:
    1. ClO2- and ClO-
    2. S2- and Te2-
    3. AsO33- and PO33-
    1. ClO- (conjugate base of the weaker acid, HClO)
    2. S2-(conjugate base of the weaker acid, H2S)
    3. AsO33-(conjugate base of the weaker acid, H3AsO3)
    400
    Estimate the pH of 0.2 M NaH2PO4(aq). For phosphoric acid: pKa1 = 2.0, pKa2 = 7.0, pKa3 = 12.5
    pH=(pKa1+pKa2)/2=(2.0+7.0)/2=4.5
    500
    For reaction A + 2B <-> C + 3D, with initial concentrations [A] = [B] = 1M, give the quadratic ICE box equation, but do not solve.
    K = [(3x)3(x)]/[(1-x)(1-2x)2]
    500
    Consider the following equilibrium for which ΔH<0:
  • 2 SO2(g) + O2(g) <---> 2 SO3(g)
    • How will each of the following changes affect an equilibrium mixture of the three gases:
    1. SO3(g) is removed from the system?
    2. the pressure in the reaction vessel is halfed?
    3. the total pressure of the system is increased by adding a noble gas?
    1. equilibrium shifts right
    2. equilibrium shifts left
    3. no effect
    500
    Name 6 of the 8 strong bases.
  • Group I -alkaline metals hydroxides:LiOH, NaOH, KOH, RbOH, CsOH, Fr(OH); and
  • Group II- alkaline earth metals hydroxides: Ca(OH)2, Sr(OH)2, Ba(OH)2
    • 500
    A generic weak acid (formula = HA) has a pKa of 4.0. If the solution pH is 3.0, what is the initial concentration of the acid?
    0.01 M
    500
    A generic weak base (formula = B) has a pKb of 5.00. If the initial concentration of the base is 0.10 M, what is the solution pH?
    11.00
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