UNIT OVERVIEW

This unit teaches you how to use balanced chemical equations to calculate exact amounts of reactants and products. These calculations are called stoichiometry (stoy-kee-OM-eh-tree).

In Lesson 1 of this topic, you learned about the mole concept and how to convert between moles, mass, and number of particles. Now you will use those skills to solve problems that chemists, pharmacists, and engineers face every day.

What You Will Learn

• How to use coefficients in balanced equations as mole ratios
• How to identify the limiting reagent — the reactant that runs out first
• How to calculate percentage yield and understand why reactions rarely give 100%
• How to find empirical formulae and molecular formulae from experimental data
• How to solve multi-step stoichiometry problems

Why This Matters

When a pharmaceutical company makes medicine, they cannot just mix chemicals and hope for the best. They must calculate exactly how much of each substance to use. Too little means weak medicine; too much could be dangerous or wasteful.

Similarly, fertiliser factories, food producers, and mining companies all rely on these calculations to work efficiently and safely.

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