Net-change rule
Keeps the time path honest by comparing the forward and reverse tendencies directly.
Starting reactant amount 14 Starting product amount 4
Concept module
Dynamic Equilibrium / Le Chatelier's Principle
Watch a reversible chemistry bench keep changing microscopically while the mixture settles toward a new balance after each disturbance.
The simulation shows a reversible chemistry bench with reactants and products visible at the same time, plus pulse cues for forward and reverse change and balance bars for the current rates. Sliders change the starting amounts and the product-favor setting. A readout card reports the current reactant amount, product amount, forward rate, reverse rate, and settled product share so the learner can compare the moving bench with the graphs. At t = 0 s, the mixture shows about 14 reactant units and 4 product units. Forward change is still winning, so the mixture is shifting toward more products. The current conditions only lean gently toward one side, so the settled mixture stays more balanced.
Interactive lab
Keep the stage, graph, and immediate control feedback in one working view.
Time
0.00 s / 12.0 sLivePause to inspect a specific moment, then step or scrub through it.0.00 s12.0 s
Dynamic equilibrium and Le Chatelier's principle
Keep the reversible particle swap, the forward-versus-reverse rates, and the shift toward a new balance on one shared chemistry bench.
Graphs
Switch graph views without breaking the live stage and time link.
Mixture over time
Shows how reactants and products move toward the settled mix.
Time: 0 to 12Amount: 0 to 32
ReactantsProducts
Controls
Adjust the live parameters and watch the bench respond.
Set how much reactant the system starts with.
Set how much product the system starts with.
Lean the final equilibrium toward products or reactants.
More tools
Secondary controls, alternate presets, and less-used toggles stay nearby without crowding the main bench.
Show
More tools
Secondary controls, alternate presets, and less-used toggles stay nearby without crowding the main bench.
More presets
Presets
Predict -> manipulate -> observe
Keep the active prompt next to the controls so each change has an immediate visible consequence.
Graph readingPrompt 1 of 1
A disturbance is only visible if the current mix and the settled target no longer match. Watch the target band and the time history together.
Equation map
See each variable before you move it.
Select a symbol to highlight the matching control and the graph or overlay it most directly changes.
Starting reactant amount
14Sets how much reactant the bench starts with before the reversible exchange begins.
Graph: Mixture over timeGraph: Forward vs reverse rateOverlay: Target mixOverlay: Balance bars
Equations in play
Choose an equation to sync the active symbol, control highlight, and related graph mapping.
More tools
Detailed noticing prompts, guided overlays, and challenge tasks stay available without taking over the main bench.
Hide
More tools
Detailed noticing prompts, guided overlays, and challenge tasks stay available without taking over the main bench.
What to notice
Stay with the same chemistry bench and read the rate bars, the current mix, and the settled target together.
Graph readingPrompt 1 of 1
A disturbance is only visible if the current mix and the settled target no longer match. Watch the target band and the time history together.
Control: Reactant amountControl: Product amountControl: Product-favor settingOverlay: Target mix
Guided overlays
Focus one overlay at a time to see what it represents and what to notice in the live motion.
3 visible
Overlay focus
Dynamic exchange
Keep the forward and reverse pulse cues visible.
What to notice
- The pulse cues can keep firing even when the overall mixture stops changing much.
Why it matters
It makes dynamic equilibrium visible instead of leaving it as a sentence in the text.
Control: Reactant amountControl: Product amountGraph: Forward vs reverse rateEquationEquation
Challenge mode
Disturb the chemistry honestly, then wait for the system to rebalance instead of treating equilibrium as an instant switch.
0/1 solved
ConditionStretch
4 of 9 checks
Disturb, then rebalance
Build a product-favored equilibrium from a reactant-heavy start, then let the forward and reverse rates come back together while the product share stays clearly above one-half.
Inspect timeGraph-linkedGuided start2 hints
Suggested start
Change the favor setting or the starting mix, then give the bench time to rebalance.
Pending
Open the Forward vs reverse rate graph.
Mixture over timeMatched
Keep the Dynamic exchange visible.
OnMatched
Keep the Balance bars visible.
OnMatched
Keep the Target mix visible.
OnMatched
Return to live time.
livePending
Let the bench run long enough to approach the new balance.
0Pending
Use a clearly product-favored setting between 1.28 and 1.4.
1.12Pending
Keep the current product share between 58% and 70%.
0.22Pending
Bring the forward-reverse rate gap down below 0.14.
2.42The checklist updates from the live simulation state, active graph, overlays, inspect time, and compare setup.
At t = 0 s, the mixture shows about 14 reactant units and 4 product units. Forward change is still winning, so the mixture is shifting toward more products. The current conditions only lean gently toward one side, so the settled mixture stays more balanced.
Equation detailsDeeper interpretation, notes, and worked variable context.
Dynamic equilibrium
Shows that equal forward and reverse rates are the real equilibrium condition, not a stopped reaction.
Starting reactant amount 14 Starting product amount 4 Product-favor setting 1.12
Shift-to-balance rule
Summarizes the Le Chatelier idea without pretending the bench is a full chemistry engine.
Product-favor setting 1.12
Progress
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Let the live model runChange one real controlOpen What to notice
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Stable links
Starter track
Step 2 of 20 / 2 completeRates and Equilibrium
Earlier steps still set up Dynamic Equilibrium / Le Chatelier's Principle.
1. Reaction Rate / Collision Theory2. Dynamic Equilibrium / Le Chatelier's Principle
Previous step: Reaction Rate / Collision Theory.
Short explanation
What the system is doing
Dynamic equilibrium becomes easier to trust when the particles keep changing even after the mixture looks settled. This module keeps reactants, products, forward change, reverse change, and the time path toward a new balance on one shared chemistry bench.
The main idea is that equilibrium does not mean stopped. It means the forward and reverse changes have become equally strong, so the visible mixture can stay steady even though the microscopic swapping keeps going.
Key ideas
01At dynamic equilibrium, forward and reverse changes are still happening, but they balance each other.
02Changing the mixture or the product-favor conditions disturbs the balance and sends the system toward a new equilibrium.
03Le Chatelier's principle is easiest to trust when the disturbance and the re-balancing path stay visible together.
Worked example
Read the full frozen walkthrough.
Frozen walkthrough
Use the current chemistry bench instead of a detached table. The same controls drive the particle scene, the time history, and these substitutions.
Live worked examples are available on Premium. You can still read the full frozen walkthrough on the free tier.
View plansFrozen valuesUsing frozen parameters
At the current time, what is the balance between forward and reverse change?
Time
0
Starting reactant amount
14
Starting product amount
4
1. Read the current mixture
At t = 0 s, the bench shows about 14 reactant units and 4 product units.
2. Read the competing rates
The forward rate is about 3.14/s while the reverse rate is about 0.71/s.
3. Read how close the system is to balance
That leaves a rate gap of about 2.42, which tells you how far the mixture still is from a balanced exchange.
Current balance
Forward change is still winning, so the mixture is moving toward more products.
Common misconception
If the amounts stop changing, the reaction itself must have stopped.
The amounts can stay steady because forward and reverse change match each other.
The microscopic exchange can continue even while the overall mixture looks settled.
Mini challenge
Disturb the mixture, then wait until the rates nearly match again while the settled mix is clearly product-favored.
Prediction prompt
Decide whether you should change the starting mixture, the favor setting, or both before you test it.
Check your reasoning
You need a disturbance that pushes the system away from its old balance and conditions that favor the product side strongly enough for the new equilibrium to land there.
That shows both halves of the idea at once: the equilibrium is dynamic because the exchange continues, and Le Chatelier's principle is about the path to a new balance after a disturbance.
Quick test
Misconception check
Question 1 of 3
Answer from the live equilibrium story, not from a slogan about the reaction being finished.
What is the cleanest description of dynamic equilibrium?
Choose one answer to reveal feedback, then test the idea in the live system if a guided example is available.
Accessible description
The simulation shows a reversible chemistry bench with reactants and products visible at the same time, plus pulse cues for forward and reverse change and balance bars for the current rates. Sliders change the starting amounts and the product-favor setting.
A readout card reports the current reactant amount, product amount, forward rate, reverse rate, and settled product share so the learner can compare the moving bench with the graphs.
Graph summary
One graph shows the reactant and product amounts over time, a second compares the forward and reverse rates over time, and a third shows the settled product share against the product-favor setting.
Graph hover, compare mode, and the shared overlays all stay attached to the same chemistry bench and do not open a separate chemistry-only view.
Carry equilibrium into the next branch
Keep moving through the concept map.
These suggestions come from the concept registry, so the reason label reflects either curated guidance or the fallback progression logic.
Reuse the particle-collision picture in a thermodynamics benchThermodynamics
Ideal Gas Law and Kinetic Theory
Connect pressure, volume, temperature, and particle number on one bounded particle box, then read the same pressure changes back as changes in particle speed and wall-collision rate.
Next in Collision theoryRates and Equilibrium
Reaction Rate / Collision Theory
Keep one chemistry box visible so temperature, concentration, activation threshold, and catalysts can be read as changes in successful collisions instead of chemistry slogans.
Useful comparisonThermodynamics
Temperature and Internal Energy
Compare average particle motion with whole-sample energy, vary amount and heating, and see why a phase-change shelf breaks naive temperature-only reasoning on one compact thermal bench.