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Chemistry · Stoichiometry and Yield

Percent Yield and Reaction Extent

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Wrap-up

What you learned

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Read next: Concentration and DilutionCarry quantity bookkeeping into solutions

Key takeaway

Find the theoretical output first from the recipe and the limiting-reagent batch cap.
Percent yield tells what fraction of that theoretical output actually forms.

Common misconception

A 75% yield means the recipe itself changed so each batch uses only 75% of the reactants.

The recipe card stays the same. You still start from the same theoretical batch cap.

Carry yield into the next chemistry branch

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Carry quantity bookkeeping into solutionsSolutions and pH

Concentration and Dilution

Use one beaker to separate how concentration changes when you add solvent from how it changes when you add more solute.

Keep the output-cap idea in a beakerSolutions and pH

Solubility and Saturation

Keep dissolved amount, excess solid, and current capacity in one beaker so saturation reads like a visible limit instead of a slogan.

Next in Limiting and excess reactantsStoichiometry and Yield

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.

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Reference and support

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Equation snapshotActual output from theoretical output · Reaction extent as a fraction of theoretical outputShow 2 equations

Actual output from theoretical output
$b_{actual} = \frac{Y}{100} b_{theory}$
Take the theoretical batch count first, then scale it by percent yield to get the actual finished output.
Reaction extent as a fraction of theoretical output
$ξ = \frac{b _{actual}}{b _{theory}}$
Reaction extent here is the fraction of the theoretical batches that actually finish.

Why it behaves this way

Explanation

Start by finding the theoretical output. Use the recipe card and the limiting-reagent cap to work out the maximum possible batches, then compare that ideal marker with the actual product tray.

On this bench, reaction extent is the fraction of those theoretical batches that really finish. Lowering percent yield does not rewrite the recipe or switch the limiting side. It only lowers the actual output below the same theoretical maximum.

Key ideas

01Find the theoretical output first from the recipe and the limiting-reagent batch cap.

02Percent yield tells what fraction of that theoretical output actually forms.

03When yield is below 100%, the missing part is a shortfall from the same theoretical marker, so more reactant stays unused.

Worked examples

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Frozen walkthrough

Step through the frozen example

Frozen walkthrough

Read the theoretical marker first, then use percent yield to predict the actual tray.

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Frozen valuesUsing frozen parameters

With 12 A, 18 B, a 2:3 recipe, and 75% yield, what actual output appears and how large is the shortfall from theoretical?

A

Reactant A packets

B

Reactant B packets

Y

Percent yield

1. Find the theoretical batch cap

The current 12 A and 18 B run supports 6 theoretical batches on the 2:3 recipe.

2. Apply percent yield to the theoretical output

At 75% yield, the actual tray reaches 4.5 product batches.

3. Compare the actual tray with the theoretical marker

The yield gap is 1.5 batches, so the tray stops short of the theoretical marker.

Actual output and yield gap

Actual output = 4.5 batches; yield gap = 1.5 batches.

The actual tray stops short of the theoretical marker because yield scales the same recipe cap down.

Quick test

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Accessibility

Open the text-first descriptions when you need the simulation and graph translated into words.

The simulation shows two reactant supply bins, a product tray, a theoretical-output marker, and a recipe card that states how many packets of A and B one full batch needs.

A readout reports the current recipe, the maximum possible batches, the limiting side, the actual output, and leftover reactant so the learner can compare theoretical and actual results.

Graph summary

One graph shows possible batches against the A supply, a second shows possible batches against the B supply, and a third compares actual product with theoretical product as percent yield changes.

Use the yield graph to see the actual-output line move while the theoretical marker stays fixed for the same recipe run.

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Featured setups

75% yield run

Open a matched run at 75% yield and compare the shorter actual tray with the unchanged theoretical marker.

Full-yield contrast

Compare the same kind of matched run at 100% yield so the actual tray reaches the theoretical marker.

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Starter track

Step 3 of 3

Stoichiometry and Yield

Percent Yield and Reaction Extent appears later in this track, so it is cleaner to start from the beginning first.

Previous step: Limiting Reagent and Leftover Reactants

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