Percentage Yield and Atom Economy
Compare theoretical and actual yield, calculate atom economy and evaluate the efficiency of industrial routes.
How to study Higher Chemistry
Move deliberately between structure, equations, quantitative models, unfamiliar evidence and justified experimental conclusions, while using current official materials for exact paper and assignment practice.
Core concepts
Concept 1
Theoretical yield follows from the limiting reactant and stoichiometry; actual yield is the product obtained experimentally.
Exam cue: Find theoretical yield from a balanced equation before calculating percentage yield.
Concept 2
Percentage yield compares actual with theoretical yield, while atom economy compares desired-product mass with the total reactant mass represented by the balanced equation.
Exam cue: Use equation coefficients in the total product mass for atom economy.
Concept 3
Industrial process choice also depends on rate, equilibrium, separation, energy, safety, feedstocks and economics.
Exam cue: Keep yield, atom economy and rate as separate measures when evaluating a process.
Risk pitfalls and guardrails
Dividing theoretical yield by actual yield.
Guardrail: Check structures, formulae, charges, equation balance, units, signs and experimental conditions before committing to the final conclusion.
Calculating atom economy from reactant masses used in one experiment.
Guardrail: Check structures, formulae, charges, equation balance, units, signs and experimental conditions before committing to the final conclusion.
Assuming the highest-yield route must be the most sustainable or economic.
Guardrail: Check structures, formulae, charges, equation balance, units, signs and experimental conditions before committing to the final conclusion.
Memory anchors
Theoretical yield
The maximum product amount predicted from the limiting reactant and balanced equation.
Actual yield
The amount of purified product actually obtained.
Percentage yield
Actual yield divided by theoretical yield, multiplied by 100.
Atom economy
Formula mass of desired product divided by total formula mass of all products, including coefficients, multiplied by 100.
High atom economy
A larger fraction of reactant atoms ends up in the desired product.
Process evaluation
Consider conversion, rate, energy, separation, safety, raw materials, waste and cost together.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is theoretical yield?
What is actual yield?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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