Dissolution equilibrium visualizer

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

About this MicroSim

This animation shows a sparingly soluble salt (AgCl, BaSO₄, PbI₂, or CaCO₃) dissolving inside a container. The bottom crystal shrinks as ions enter solution, particles move randomly in the solvent, and a live chart reports [cation], [anion], and the ion product Q relative to Ksp. Buttons inject a common ion or more solid to reveal how equilibrium responds, while a temperature slider demonstrates faster or slower dissolution kinetics.

How to use

1. Pick a salt preset to load its Ksp and initial crystal size.
2. Watch ions dissolve until the Q marker meets Ksp and the status reads “Equilibrium!”.
3. Click Add common ion to flood the solution with the shared anion and observe Q > Ksp, precipitation, and a regrowing crystal.
4. Use Add more solid to drop additional crystal mass; if Q < Ksp, dissolution resumes.
5. Adjust the Temperature slider to speed up or slow down the forward/reverse rates.
6. Read the bottom info bar for the formula, Ksp value, molar solubility, and live Q.

Classroom ideas

• Compare two salts’ equilibrium particle counts and relate them to Ksp magnitudes.
• Use screenshots of the Q vs Ksp chart before and after adding a common ion to explain Le Chatelier’s principle.
• Run the simulation twice, once at low temperature and once high, to discuss kinetic vs thermodynamic effects.
• Ask students to predict how much the crystal regrows after a common-ion addition, then verify in the sim.

Learning goals

Item	Details
Subject area	Chemistry — solubility equilibria
Grade band	Grades 11–12 and introductory college
Learning objective	Students will describe how dissolution reaches dynamic equilibrium and explain how the common-ion effect shifts Q relative to Ksp.
Bloom's level	Understand / Analyze
Duration	10 minutes
Prerequisites	Ksp expressions, ion product comparisons, qualitative idea of the common-ion effect
Assessment ideas	Prompt students to capture Q and status before/after a common-ion addition, or to explain why adding more solid does not change Q once equilibrium is reached

Instructional design review

• Single objective: “Students will explain how Q approaches Ksp and how a common ion suppresses solubility.” ✔️
• Control inventory:

Control	Type	Purpose
Salt selector	Dropdown	Choose Ksp/stoichiometry preset
Add common ion	Button	Injects shared ion to force precipitation
Add more solid	Button	Adds solid mass for dissolution
Temperature	Slider	Adjusts dissolution/precipitation rates
Reset	Button	Returns to initial state

• Progressive disclosure: The status card and Q vs Ksp bar update automatically; no extra modals required.
• Cognitive load: Particle animation, chart, and text box remain in fixed panels; controls stay beneath the canvas per the p5 guide.

Lesson plan

Grade level

AP Chemistry Unit 9 (solubility equilibria) or introductory college chemistry

Duration

10-minute teacher demo plus 5-minute student exploration

Prerequisites

• Writing Ksp expressions from dissolution equations
• Comparing Q to Ksp to predict precipitation
• Conceptual understanding of Le Chatelier’s principle

Activities

1. Launch (3 min): Demonstrate dissolution reaching equilibrium for AgCl and highlight the live Q trace.
2. Common-ion test (5 min): Students predict what happens before pressing “Add common ion,” then record observations.
3. Extension (2 min): Use the temperature slider to discuss kinetic vs thermodynamic factors in solubility.

Assessment

• Exit ticket: “Explain why adding more solid at equilibrium does not change Q unless the solution is undersaturated.”
• Screenshot reflection: Students capture the chart before and after common-ion addition and describe the shift.

References

1. Tro, N. J. Chemistry: A Molecular Approach, 5th ed., Pearson, 2020 — Common-ion effect and Ksp calculations.
2. Zumdahl & Zumdahl. Chemistry, 11th ed., Cengage, 2020 — Dynamic dissolution equilibrium diagrams.