Chapter 4
Quantities of Substances: Chemical Calculations
The mole, molar mass, empirical formulas, balancing equations, stoichiometry, concentration, percentage yield and atom economy — every core A-Level chemistry calculation, worked through step by step.
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Measuring Amounts of Substance
Formulas and Equations
Reacting Quantities
Concentration and Yield
Try it yourself
🔬 Balancing Chemical Equations
Balance chemical equations by adjusting coefficients, with a bar-chart check of atoms on each side.
Try this: Change the coefficient in front of each reactant and product to balance the equation.
Look for: Use the "Tools" bar chart — it only shows equal bars on both sides once the equation is truly balanced.
Simulation by PhET Interactive Simulations, University of Colorado Boulder — licensed CC BY-NC. View on phet.colorado.edu ↗