⚖️ Molar Master
Level 3 · SL+HL · NEW 2025
← All Experiments
Reactivity 2.1
🎯 Reaction Setup
Category
Organic Synthesis
Inorganic Production
Green Chemistry Comparison
🔄 Generate Problem
👁 Reveal
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⚗️ Reaction
Click "Generate Problem" to begin
Mr of desired product
—
Total Mr of all products
—
🧮 Your Calculation
Mr of desired product:
g mol⁻¹
Total Mr of all products:
g mol⁻¹
Atom Economy (%):
%
✓ Check Answer
—
Desired Product
—
Waste / By-products
Correct
0
Attempted
0
Accuracy
—
💡 Concept
♻️ Green Chemistry
📝 Exam Tip
Atom Economy
Atom economy
= (Mr of desired product / total Mr of all products) × 100%
It measures how efficiently atoms from reactants end up in the desired product
Addition reactions
have 100% atom economy (all atoms → one product)
Substitution and elimination
reactions produce by-products → lower atom economy
Different from
% yield
: atom economy is theoretical (from equation), yield is experimental
Green Chemistry Connection
Principle 2
of Green Chemistry: maximize atom economy to minimize waste
High atom economy reduces cost, waste disposal, and environmental impact
Industry prefers catalytic reactions (rearrangements, additions) over stoichiometric substitutions
Example: making ethanol by
addition of H₂O to ethene
(100% AE) vs
fermentation
(produces CO₂ waste)
NEW in 2025 syllabus
: students must connect atom economy to sustainability
IB Exam Strategies
Step 1
: Write balanced equation
Step 2
: Calculate Mr of desired product (considering stoichiometric coefficients)
Step 3
: Calculate total Mr of ALL products (including by-products)
Step 4
: AE = Mr(desired) / Mr(all products) × 100
Common trap
: don't forget to multiply Mr by stoichiometric coefficients!
AE vs Yield
: atom economy tells you about waste DESIGN; yield tells you about efficiency of execution