UNIT OVERVIEW

Stoichiometry means "measuring elements." Think of it as the recipe book of chemistry. Just as a baker needs exact amounts of flour, sugar, and eggs for a perfect cake, chemists need precise amounts of reactants to produce desired products.

You already know how to balance chemical equations and work with the mole concept from Grade 10. Now you will combine these skills. By the end of this unit, you will be able to:

• Calculate the volume of gases at Standard Temperature and Pressure (STP)
• Determine the concentration of solutions and perform dilution calculations
• Identify limiting reagents and excess reagents in chemical reactions
• Calculate theoretical yield and percentage yield
• Apply volume relationships in gaseous reactions
• Perform comprehensive stoichiometric calculations from balanced equations

Why stoichiometry matters:

• Medicine: Pharmaceutical companies calculate exact quantities of active ingredients. Too little means an ineffective drug; too much could be dangerous.
• Agriculture: Fertiliser production requires stoichiometric calculations to determine how much nitrogen and hydrogen are needed to produce ammonia.
• Mining: Calculating how much cyanide solution is needed to extract gold from ore, or how much ore must be processed to obtain a certain mass of pure metal.
• Environment: Determining how much limestone is needed to neutralise acid mine drainage, or how much chlorine to add to purify water supplies.

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