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Auto-Ionization quiz

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  • What is auto-ionization (self-ionization) of water?
    Auto-ionization is the process where two water molecules react to form hydronium (H3O+) and hydroxide (OH-) ions.
  • According to Bronsted-Lowry theory, what role does each water molecule play during auto-ionization?
    One water molecule acts as an acid (donates H+), and the other acts as a base (accepts H+).
  • What ions are produced when water undergoes auto-ionization?
    Hydronium ion (H3O+) and hydroxide ion (OH-) are produced.
  • How is the reaction between two water molecules simplified in textbooks?
    It is often shown as water splitting into H+ and OH- ions, though this is not how water actually behaves.
  • What is the relationship between H+ and H3O+ ions in aqueous solutions?
    H+ is a simplified representation of H3O+; they are considered equivalent in calculations.
  • What is the equilibrium constant for the auto-ionization of water called?
    It is called the ion product constant, or Kw.
  • How is Kw calculated for the auto-ionization of water?
    Kw is the product of the concentrations of H+ and OH- ions: Kw = [H+][OH-].
  • Why are solids and liquids ignored in the equilibrium expression for Kw?
    Solids and liquids are ignored because their concentrations do not change during the reaction.
  • What is the standard value of Kw at 25°C?
    The standard value of Kw at 25°C is 1.0 x 10^-14.
  • How does temperature affect the value of Kw?
    Kw is heavily temperature dependent; changing the temperature changes the value of Kw.
  • If the temperature changes, what must be provided for calculations involving Kw?
    A new value for Kw must be given, since it varies with temperature.
  • Why is understanding Kw important in analytical chemistry?
    Understanding Kw is crucial for calculating and relating the concentrations of hydronium and hydroxide ions in aqueous solutions.
  • If you know the concentration of H+ in water, how can you find the concentration of OH-?
    You can use Kw = [H+][OH-] to solve for the unknown concentration.
  • What is ignored in the equilibrium expression for the auto-ionization of water?
    The concentration of liquid water is ignored in the equilibrium expression.
  • What connects the hydronium ion concentration to the hydroxide ion concentration in water?
    The ion product constant, Kw, connects the concentrations of hydronium and hydroxide ions.