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Acid–base neutralization

Mix acid and base and check the remaining ions and BTB color.

    C08 · Acid–base neutralizationReady
    Mix acid and base and check the remaining ions and BTB color. You can also experiment with the numbers and controls below.

    Chemistry · Acid · Base / Principles and Exploration

    Acid–base neutralization — principles and investigation

    When mixing an acid and a base, neutrality is not determined solely by the volume of the two solutions. Change the concentration and volume of hydrochloric acid and sodium hydroxide and compare the number of moles of hydrogen ions and hydroxide ions. This is an experiment to distinguish between ions that directly participate in the reaction and bystander ions that remain after the reaction.

    How does it work?

    All of the ions on the smaller side react and the more ions remain. The number of moles of Na⁺·Cl⁻ before and after the reaction is the same.

    Key relationship

    H⁺ + OH⁻ → H₂O · n = cV

    Try this investigation

    1. Set the concentration and volume and mix. Compare the batches of particles before and after the reaction in the two beakers, and check the actual number of particles in the table.
    2. Mix 30 mL and 50 mL of base with 50 mL of acid and record. The concentrations are all 0.1 mol/L.
    3. Under standard conditions, change only the base volume to 70 mL or change only the base concentration to 0.20 mol/L and record.

    Interpreting your results

    What condition defines the neutralization equivalence point?

    In monovalent strong acids and strong bases, when c acid (V acid) = c base (V base), H⁺ and OH⁻ are not left. Na⁺·Cl⁻ remains as a spectator ion.

    Assumptions and limitations

    It is a monovalent strong acid/strong base model in which HCl·NaOH completely dissociates. Precise pH, automatic ionization of water, and heat of reaction are not covered. BTB is an introductory classification of acid yellow, neutral green, and basic blue, and the actual discoloration section is omitted. The dots are a group picture, and the actual numbers are indicated as N=nNₐ in the table.