3a. Amounts of Substances
6 lessons · Moles, formula mass, and what the numbers in equations really mean.
01Relative Formula Mass
If you're struggling to calculate the mass of chemical compounds, this video gives you a clear, step-by-step method. You'll learn what relative atomic mass and relative formula mass actually mean, where to find the values you need, and how to apply them to both simple molecules and ionic compounds with brackets. By the end you'll be able to calculate Mr for any compound — the essential first step in almost every quantitative chemistry calculation.
02The Mole
The mole is one of those ideas that sounds mysterious until someone explains it simply — and this video does exactly that. You'll discover where the concept came from, what Avogadro's constant actually means, and how the core equation (moles = mass ÷ Mr) connects the invisible world of atoms to the masses you weigh in a laboratory. By the end you'll have both the conceptual understanding and the calculation skill you need to go further in quantitative chemistry.
03Conservation of Mass
This video starts with Lavoisier's 18th-century experiments and uses them to show why the Law of Conservation of Mass isn't just a rule to memorise — it's a consequence of the fact that atoms are never created or destroyed in a chemical reaction. You'll see why reactions that appear to gain or lose mass are really just losing gases to or gaining them from the surroundings, and you'll work through the calculation method that lets you find a missing mass from a balanced equation.
04The Mole and Equations
05Limiting Reactants
06Volumes of Gases
3b. Concentrations
3 lessons · Working with solutions — calculating and comparing concentrations.
01Introduction to Concentrations
02More on Concentrations
03Concentration Calculations
3c. Atom Economy and Yield
3 lessons · Measuring efficiency — how much of a reaction actually becomes useful product.
01Atom Economy
02Percentage Yield
03