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Buffer system visualizer

Run the Buffer Visualizer fullscreen
Edit the MicroSim in the p5.js editor

About this MicroSim

Two beakers—one buffer, one pure water—sit beneath a shared pH scale. Adjust the initial HA and A⁻ concentrations, set \(pK_a\), and then add strong acid or base. The buffer’s pH shifts according to Henderson-Hasselbalch and particle ratios animate accordingly, while the water column swings dramatically, highlighting buffer resistance.

How to use

  1. Move the [HA] and [A⁻] sliders (0.01–1.0 M). The particle mix updates immediately.
  2. Set the \(pK_a\) slider (2–12) to choose the acid/base pair.
  3. Use the Add to buffer dropdown to select a strong acid/base slug, then press Add. Concentrations update according to stoichiometry and pH is recalculated.
  4. Compare buffer vs. water pH change and \(\Delta pH\) readouts; watch the pointers on the shared pH scale.

Learning goals

Item Details
Subject area Chemistry — buffers
Grade band AP Chemistry / introductory college
Learning objective Students will analyze how HA/A⁻ ratios and additions of strong acids/bases affect buffer pH compared to pure water.
Bloom's level Analyze
Duration 10 minutes
Prerequisites Henderson-Hasselbalch equation, acid/base stoichiometry
Assessment ideas Students record initial/final pH and \(\Delta pH\) for two additions; exit ticket explains why buffers resist change.

Instructional design review

  • Single objective: “Explain why buffers resist pH changes relative to water.” ✔️
  • Controls: three sliders, one dropdown, and an Add button—within the guide’s limits.
  • Progressive disclosure: Calculated values update continuously; additions occur only after pressing the button.
  • Accessibility: Large fonts, consistent color coding (orange HA, blue A⁻), cursor-friendly controls beneath the canvas.

Lesson plan

  1. Demo (3 min): Show equal HA/A⁻ buffer vs. pure water; note initial pH.
  2. Student exploration (5 min): Learners test two additions (acid and base) while logging buffer vs. water \(\Delta pH\).
  3. Discussion (2 min): Share how HA/A⁻ ratios or \(pK_a\) closer to target pH improve buffering.

References

  1. Zumdahl & Zumdahl. Chemistry, 11th ed., Cengage, 2020 — Buffer calculations.
  2. Tro, N. J. Chemistry: A Molecular Approach, 5th ed., Pearson, 2020 — Henderson-Hasselbalch applications.