HomeConcept libraryChemistryStoichiometry and YieldStoichiometry and Yield

Chemistry Stoichiometry and YieldIntroStarter track

Concept module

Limiting Reagent and Leftover Reactants

Use one recipe bench to see which reactant caps the output first and why the other reactant can remain in excess.

Interactive lab

Keep the stage, immediate control feedback, and linked study tools in one working bench.

Stoichiometry recipe bench

Keep the recipe card, the two reactant supplies, and the actual product output on one bench so ratios, limiting packets, and yield never drift into detached worksheet algebra.

Controls

Adjust the live parameters and watch the bench respond.

Reactant A packets

A

Change how many A packets the current run starts with.

Reactant B packets

B

Change how many B packets the current run starts with.

A per batch

a

Set how much A one full recipe batch consumes.

B per batch

b

Set how much B one full recipe batch consumes.

More tools

Secondary controls, alternate presets, and less-used toggles stay nearby without crowding the main bench.

Show

Percent yield

100 %

Keep this at 100% here so the limiting-reagent story stays isolated.

More presets

Presets

Predict -> manipulate -> observe

Keep the active prompt next to the controls so each change has an immediate visible consequence.

ObservationPrompt 1 of 2

The limiting reagent is the side with the lower recipe-supported batch cap, not the side with the smaller raw count.

Graphs

Switch graph views without breaking the live stage and time link.

Possible batches vs A supply

Watch the possible batch count rise until the fixed B supply becomes the cap.

reactant A packets: 2 to 18recipe batches: 0 to 8

Possible batchesB supply cap

Hover or scrub to link the graph back to the stage.reactant A packets / recipe batches

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.

A

Reactant A packets

Sets how many full batches A can support before it runs out.

Graph: Possible batches vs A supplyOverlay: Recipe cardOverlay: Limiting cue

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

What to notice

Keep the lower cap line and the leftover tray readout in view together.

ObservationPrompt 1 of 2

Graph: Possible batches vs A supply

The limiting reagent is the side with the lower recipe-supported batch cap, not the side with the smaller raw count.

Control: Reactant A packetsControl: Reactant B packetsControl: A per batchControl: B per batchGraph: Possible batches vs A supplyGraph: Possible batches vs B supplyOverlay: Recipe cardOverlay: Limiting cueEquation

A

Equation

B

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

Recipe card

Keep the reaction recipe visible while the supply bins change.

What to notice

Limiting reagent only makes sense relative to the recipe card, not raw counts alone.

Why it matters

It keeps the limiting-reagent decision attached to one visible recipe instead of a detached arithmetic trick.

Control: A per batchControl: B per batchGraph: Possible batches vs A supplyGraph: Possible batches vs B supplyEquation

a

Equation

b

Challenge mode

Build a run where B is limiting and A is clearly left over.

0/1 solved

ConditionCore

5 of 8 checks

Make B limit first

Keep the 2 A + 3 B recipe, but set the supplies so B is limiting and 3 A packets remain after the full-yield run.

Graph-linkedGuided start2 hints

Pending

Open the Possible batches vs B supply graph.

Possible batches vs A supply

Matched

Keep the Recipe card visible.

Matched

Keep the Limiting cue visible.

Matched

Keep A per batch at 2.

Matched

Keep B per batch at 3.

Pending

Set A to 9 packets.

Pending

Set B to 9 packets.

Matched

Keep yield at 100% so the leftover comes only from excess reactant.

100

The checklist updates from the live simulation state, active graph, overlays, inspect time, and compare setup.

The current recipe is 2 A + 3 B -> 1 batch. With 8 A and 15 B, the run can support about 4 full batches. Reactant A runs out first, so extra B remains after the last full batch. At full yield, the actual output reaches the theoretical batch count.

Equation detailsDeeper interpretation, notes, and worked variable context.

Reactant-supported batch counts

Each supply supports its own number of complete batches once you divide by the packets required per batch.

b_{A} = \frac{A}{a}, b_{B} = \frac{B}{b}

A

Reactant A packets 8

B

Reactant B packets 15

a

A per batch 2

b

B per batch 3

Theoretical batch cap

The smaller of the two reactant-supported batch counts sets the theoretical output.

b_{theory} = min (b_{A}, b_{B})

A

Reactant A packets 8

B

Reactant B packets 15

a

A per batch 2

b

B per batch 3

Leftover excess reactant

The excess side keeps whatever packets are not spent in the completed theoretical batches.

L_{excess} = N_{excess} - b_{theory} n_{recipe}

B

Reactant B packets 15

b

B per batch 3

Progress

Not startedMastery: NewLocal-first

Start exploring and Open Model Lab will keep this concept's progress on this browser first. Challenge mode has 1 compact task ready. No finished quick test, solved challenge, or completion mark is saved yet.

Let the live model runChange one real controlOpen What to notice

Try this setup

Jump to a named bench state or copy the one you are looking at now. Shared links reopen the same controls, graph, overlays, and compare context.

This bench opened from a setup link. Any new copy will reflect the state you see now.

Current bench

A limits first preset

This bench still matches one named preset, so the copied link will reopen that same starting point along with the current graph, overlays, and inspect context.

Open default bench

Featured setups

A caps first

Open the run where A sets the batch cap and B is left over.

B caps first

Flip to a run where B runs out first and A stays on the bench.

Saved setups

Premium keeps named exact-state study setups in your account while stable concept links stay public below.

Checking saved setup access.

This concept can keep using stable links while the saved-setups capability resolves for this browser.

Copy current setup

Stable concept and section links stay public below while exact-state setup sharing stays behind premium.

Stable links

Starter track

Step 2 of 30 / 3 complete

Stoichiometry and Yield

Earlier steps still set up Limiting Reagent and Leftover Reactants.

1. Stoichiometric Ratios and Recipe Batches2. Limiting Reagent and Leftover Reactants3. Percent Yield and Reaction Extent

Previous step: Stoichiometric Ratios and Recipe Batches.

Start from track beginning

Short explanation

What the system is doing

Limiting reagent makes more sense when the lower recipe-supported cap stays visible beside the actual supply trays. This bench keeps both reactant bins, the recipe card, and the leftover readout together so the limiting step never turns into hidden algebra.

The limiting reagent is just the reactant that can support fewer complete recipe batches. The other reactant is excess, so some of it remains once the last full batch finishes.

Key ideas

01Each reactant supply supports its own possible batch count when you divide by the recipe packets required per batch.

02The smaller batch count sets the theoretical output because the reaction cannot finish more full batches than that.

03Leftover reactant belongs to the excess side, not to the limiting side.

Worked example

Read the full frozen walkthrough.

Frozen walkthrough

Read the lower cap directly from the recipe bench.

Live worked examples are available on Premium. You can still read the full frozen walkthrough on the free tier.

View plans

Frozen valuesUsing frozen parameters

Which supply is limiting in the 8 A, 15 B run, and what remains after the full-yield reaction?

A

Reactant A packets

reactantAAmountValue

B

Reactant B packets

reactantBAmountValue

b

B per batch

recipeBValue

1. Convert each supply into possible batches

A can support 8 / 2 = 4 full batches, while B can support 15 / 3 = 5 full batches.

2. Read the lower cap as the limiting reagent

Because four batches is the smaller cap, A is the limiting reagent and the theoretical output is four batches.

3. Spend the recipe and read what stays behind

Four full batches spend 12 B packets, so 3 B packets remain while A is fully used.

Limiting side

A limits; 3 B packets remain.

The limiting reagent is the first supply to run out once the recipe spends complete batches only.

Common misconception

The reactant with the smaller raw packet count must always be the limiting reagent.

Limiting depends on the recipe card as well as the raw supply counts.

A larger raw count can still be limiting if each batch consumes that reactant more heavily.

Mini challenge

Make one reactant cap the recipe while the other clearly stays in excess.

Prediction prompt

Decide which supply must have the lower recipe-supported batch count before you move the sliders.

Check your reasoning

The limiting reagent is whichever side supports fewer complete batches on the recipe card.

Once you compare both batch caps on the same bench, the leftover story follows automatically from the excess side.

Quick test

Reasoning

Question 1 of 2

Answer from the visible batch caps and leftovers, not from a memorized slogan.

On a 2:3 recipe with 8 A and 15 B, which supply is limiting?

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 two reactant supply bins, one product tray, and a recipe card that states how many packets of A and B one full batch needs.

A readout card reports the current recipe, the maximum possible batches, which supply is limiting, the actual output, and how much of each reactant is left after the run.

Graph summary

One graph scans possible batches against the A supply, a second scans possible batches against the B supply, and a third keeps actual output against the theoretical product marker as percent yield changes.

The limiting cue and leftover readout stay tied to the same recipe bench instead of leaving the particle view.

Carry the capped recipe into real output

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.

Lower the actual outputStoichiometry and Yield

Limiting Reagent and Leftover Reactants

See each variable before you move it.

Recipe card

Make B limit first

Stoichiometry and Yield

What the system is doing

Read the full frozen walkthrough.

Which supply is limiting in the 8 A, 15 B run, and what remains after the full-yield reaction?

On a 2:3 recipe with 8 A and 15 B, which supply is limiting?

Keep moving through the concept map.

Percent Yield and Reaction Extent

Concentration and Dilution

Stoichiometric Ratios and Recipe Batches