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Conjugate Acid-Base Pairs

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    Chemical Concept Demonstrated

    • Strengths of acids and their conjugate bases

    Demonstration and Explanations

    1. Compare HCl, HOAc, NaCl, and NaOAc: HCl is a stronger acid than HOAc. NaCl is a weaker base than NaOAc. Stronger acids have weaker conjugate bases.

    HCl + NaOAc ---> HOAc + NaCl
    stronger acid   stronger base   weaker conjugate acid   weaker conjugate base

    2. Compare HCl, NaOH, and NaCl: HCl is a stronger acid than water. NaCl is a weaker base than NaOH. Strong acids react with strong bases to form weaker acids and bases.

    HCl + NaOH ---> H2O + NaCl
    stronger acid   stronger base   weaker conjugate acid   weaker conjugate base

    3. Compare NaOH, NH3, and H2O, and NH4Cl: NaOH is a stronger base than NH3. Water is a weaker acid than NH4Cl. Weaker bases have stronger conjugate acids. NH3 is a weak base, but its conjugate acid, NH4Cl, is a strong acid.

    NH4Cl + NaOH ---> H2O + NH3
    stronger acid   stronger base   weaker conjugate acid   weaker conjugate base

    Contributors

    Conjugate Acid-Base Pairs is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by George Bodner.

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