“Some Basic Concepts: Advanced Problem Workshop” is available to Standard subscribers.
Harder mole problems of the kind JEE and NEET set: mixtures and average molar mass, reactions in sequence, yield and purity, and titrations, each worked step by step, with a full timed paper.
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Mixtures and average molar mass: A mixture of gases behaves as if it had one molar mass: the average, weighted by the mole fractions. The vapour density is half the molar mass. From the average you can work back to the composition, and a mixture of two solids that react is solved with two equations, one for the mass and one for the moles.
Yield, purity and reactions in sequence: Real reactions give less than the equation promises, and real reactants are rarely pure. The percent yield compares the product made with the theoretical yield. The purity tells how much of a sample can react. A chain of reactions is solved by following one element from the start to the end.
Titrations and dilution: Diluting a solution adds solvent but no solute, so the moles stay the same. Mixing two solutions of one solute adds their moles and their volumes. A titration finds an unknown molarity from the volume that just reacts, with the mole ratio of the equation. A back titration measures a solid that does not dissolve.