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Acid Dissociation Constant quiz #1 Flashcards

Acid Dissociation Constant quiz #1
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  • What does the acid dissociation constant (Ka) represent, and how does its value relate to acid strength?
    The acid dissociation constant (Ka) represents the equilibrium constant for an acid's dissociation in water, measuring the tendency of an acid to donate hydrogen ions. A higher Ka value indicates a stronger acid, as it dissociates more readily to release hydrogen ions.
  • How are Ka and pKa related, and what does a higher pKa value indicate about an acid's strength?
    Ka and pKa are related by the equation pKa = -log(Ka). A higher pKa value indicates a weaker acid, as pKa and acid strength have an inverse relationship: the larger the pKa, the less the acid dissociates.
  • What does the acid dissociation constant (Ka) measure in an acid?
    Ka measures the equilibrium constant for an acid's dissociation in water, indicating the acid's tendency to donate hydrogen ions.
  • How does the value of Ka relate to the strength of an acid?
    A higher Ka value means the acid is stronger because it dissociates more readily to release hydrogen ions.
  • What is the relationship between Ka and pKa?
    pKa is the negative logarithm of Ka, given by the equation pKa = -log(Ka).
  • What does a higher pKa value indicate about an acid's strength?
    A higher pKa value indicates a weaker acid, as pKa and acid strength are inversely related.
  • How many Ka values does a polyprotic acid like phosphoric acid (H3PO4) have, and why?
    A polyprotic acid has multiple Ka values, one for each acidic hydrogen atom that can dissociate.
  • In a polyprotic acid, which acidic hydrogen is the strongest and how can you tell?
    The first acidic hydrogen is the strongest, as it has the largest Ka value among the dissociation steps.
  • Why are pKa values often used instead of Ka values in calculations?
    pKa values are used because Ka values can be extremely large or small, making pKa a more manageable scale for expressing acid strength.
  • Given two acids, one with a large Ka and one with a small Ka, which is stronger and how do their pKa values compare?
    The acid with the larger Ka is stronger, and it will have a smaller pKa compared to the weaker acid with a smaller Ka.