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Activity Coefficients quiz

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  • What does an activity coefficient (b) of 1 indicate about a solution's behavior?
    An activity coefficient of 1 indicates ideal behavior, meaning all ions are treated equally and the solution behaves ideally.
  • How is the activity (A) of a compound calculated using concentration and activity coefficient?
    Activity is calculated as A = [C] × γ, where [C] is the concentration and γ is the activity coefficient.
  • What is the purpose of the activity coefficient in solution chemistry?
    The activity coefficient is used to determine whether a solution behaves ideally or non-ideally by accounting for differences in ion size and charge.
  • What equation relates activity coefficients to ionic strength, charge, and size?
    The Extended Debye-Hückel Equation relates activity coefficients to ionic strength (μ), ionic charge (Z), and ionic size (α).
  • How does increasing ionic strength affect the activity coefficient?
    Increasing ionic strength causes the activity coefficient to decrease, showing an inverse relationship.
  • What happens to the activity coefficient as ionic strength approaches zero?
    As ionic strength approaches zero, the activity coefficient approaches unity (1), indicating ideal behavior.
  • How does ionic charge (Z) affect the activity coefficient?
    Larger ionic charges cause the activity coefficient to deviate further from unity, indicating more non-ideal behavior.
  • What is the effect of ionic size (α) on the activity coefficient?
    Smaller ionic sizes result in greater effects on the activity coefficient, causing more deviation from ideality.
  • Why are activity coefficients important in equilibrium expressions?
    Activity coefficients adjust equilibrium expressions to account for non-ideal behavior of ions in solution.
  • What does it mean if all ions in a solution are treated the same?
    It means the solution is behaving ideally, and the activity coefficient is equal to 1.
  • What is interpolation used for in the context of activity coefficients?
    Interpolation is used to estimate missing activity coefficients when specific ionic strengths are not found on standard charts.
  • How do you set up the interpolation ratio for finding a missing activity coefficient?
    The ratio is: unknown activity coefficient interval/change in activity coefficient = known ionic strength interval/change in ionic strength.
  • What unit is typically used for ionic size (α) in the Debye-Hückel equation?
    Ionic size is typically measured in picometers, though other units like nanometers can be used.
  • Why do real solutions rarely behave ideally?
    Real solutions rarely behave ideally because ions have different sizes and charges, leading to varying influences on each other.
  • What does the activity coefficient reveal about the interactions between ions in a solution?
    The activity coefficient reveals the extent to which ions deviate from ideal behavior due to differences in size and charge.