Equivalent weights by class of substance, every concentration unit with its conversion, primary versus secondary standards, and N₁V₁ = N₂V₂ across twelve numericals worked forward and checked back.
Unit 1, Physical chemistry, carries 17 of the 50 chemistry marks — joint-heaviest in the subject. With fourteen chapters sharing them, this one averages a little over one (MEC publishes weights by unit, not by chapter). It is one of the two chapters in the unit that is almost pure arithmetic, so the marks here are the most reliably earned in Chemistry.
The MEC scope line runs: Equivalent weights. Concentration: percentage, g/L, normality, molarity, molality, formality, ppm, ppb and mole fraction. Primary and secondary standard substances. Law of equivalence and the normality equation. Related numerical problems. The headings below are its points, in MEC's order.
Three ways it comes: recall (the equivalent weight of Na₂CO₃, which substances are primary standards); understanding (why molality and not molarity is used when a solution is heated, why NaOH cannot be a primary standard); application (a burette reading turned into a concentration, a dilution, a back titration).
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