Skip to main content
Back

Polyprotic Acid quiz #1

Control buttons has been changed to "navigation" mode.
1/11

Terms in this set (11)

  • What defines a polyprotic acid and can you give examples?
    A polyprotic acid is an acid that can donate more than one proton (H+) per molecule. Examples include sulfuric acid (H2SO4), carbonic acid (H2CO3), and phosphoric acid (H3PO4).
  • What is the general formula for a triprotic acid?
    The general formula for a triprotic acid is H3A, where A represents the rest of the molecule.
  • Which equilibrium constant is associated with the removal of the first acidic hydrogen from a triprotic acid?
    Ka1 is the equilibrium constant for the removal of the first acidic hydrogen from a triprotic acid.
  • How does the magnitude of Ka values change as more protons are removed from a polyprotic acid?
    Ka1 is always the largest, and each subsequent Ka value (Ka2, Ka3) is smaller, making it harder to remove each additional proton.
  • What is the fully basic form of a triprotic acid called?
    The fully basic form of a triprotic acid is A3-, which has no acidic hydrogens left.
  • How are the Ka and Kb values of a triprotic acid related to Kw?
    Multiplying corresponding Ka and Kb pairs (Ka1 × Kb3, Ka2 × Kb2, Ka3 × Kb1) gives Kw, which is 1.0 × 10⁻¹⁴ at 25°C.
  • What is the significance of the intermediate forms in a polyprotic acid?
    Intermediate forms occur after the loss of one or two acidic hydrogens and have unique equilibrium expressions and pH calculation methods.
  • When calculating the pH of the first intermediate form of a triprotic acid, which Ka values are used?
    For the first intermediate, Ka1 and Ka2 are used in the calculation of H+ concentration.
  • What is the formula for calculating the pH of the second intermediate form of a triprotic acid?
    The formula uses Ka2 and Ka3, along with the initial concentration of the second intermediate, to find H+ concentration.
  • How does temperature affect the value of Kw in polyprotic acid calculations?
    Kw is 1.0 × 10⁻¹⁴ at 25°C, but changes in temperature will alter the value of Kw, which must be provided if different.
  • When carbonic acid (H2CO3) dissociates in water, what are the main products formed in each step of its dissociation?
    Carbonic acid (H2CO3) is a diprotic acid and dissociates in two steps: first, it loses one hydrogen ion (H+) to form bicarbonate (HCO3−); then, bicarbonate can lose another H+ to form carbonate (CO3^2−). So, the dissociation steps are: H2CO3 → HCO3− + H+; then HCO3− → CO3^2− + H+.