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Diprotic Acid quiz

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Terms in this set (15)

  • What is a diprotic acid?
    A diprotic acid is a compound that can donate two H+ ions.
  • What is the general formula for a diprotic acid?
    The general formula for a diprotic acid is H2A, where H2 represents two acidic hydrogens and A is the nonmetal portion.
  • What do Ka1 and Ka2 represent for diprotic acids?
    Ka1 is the acid dissociation constant for the first H+ donation, and Ka2 is for the second H+ donation.
  • How do the values of Ka1 and Ka2 typically compare?
    Ka1 is always greater than Ka2 because it is easier to donate the first H+ than the second.
  • What is the equilibrium expression for the first dissociation of a diprotic acid?
    The equilibrium expression is Ka1 = [H3O+][HA-] / [H2A].
  • What is the equilibrium expression for the second dissociation of a diprotic acid?
    The equilibrium expression is Ka2 = [H3O+][A2-] / [HA-].
  • What are the three major forms of a diprotic acid as it loses protons?
    The three forms are H2A (acidic form), HA- (intermediate form), and A2- (basic form).
  • What is the general formula for a diprotic base?
    The general formula for a diprotic base is A2-, indicating it can accept two H+ ions.
  • What are Kb1 and Kb2 for diprotic bases?
    Kb1 is the base dissociation constant for accepting the first H+, and Kb2 is for accepting the second H+.
  • How are Ka and Kb values related for diprotic acids and bases?
    Ka1 is connected to Kb2 and Ka2 is connected to Kb1, and their products equal Kw (1.0 x 10^-14 at 25°C).
  • Which constant would you use to calculate pH for H2A in solution?
    You would use Ka1, treating H2A as a monoprotic acid.
  • What property does the intermediate form (HA-) of a diprotic acid have?
    The intermediate form (HA-) is amphoteric, meaning it can act as either an acid or a base.
  • When would you use Ka2 or Kb2 for the intermediate form of a diprotic acid?
    Use Ka2 if it donates an H+ (acts as an acid), or Kb2 if it accepts an H+ (acts as a base).
  • Why is it more difficult to remove the second proton from a diprotic acid?
    After the first proton is removed, the remaining species is more negatively charged, making it harder to remove the second proton.
  • What is the value of Kw at 25°C, and how does it relate to Ka and Kb?
    Kw is 1.0 x 10^-14 at 25°C, and for diprotic acids and bases, Ka1 x Kb2 = Kw and Ka2 x Kb1 = Kw.