Edexcel Certificate Chemistry Past Papers & Mark Schemes

Molar calculation questions in Paper 1 require a systematic approach. Always start by writing the balanced symbol equation, then work from the given substance to the unknown using mole ratios. For limiting reagent questions, calculate the moles of both reactants and identify which runs out first. For percentage yield, remember: % yield = (actual yield ÷ theoretical yield) × 100. Show every step clearly even when the arithmetic is simple — method marks are awarded even if you reach an incorrect final answer. Organic chemistry in Paper 2 requires knowledge of reaction mechanisms and functional group interconversions. Know the key reactions: addition of HBr across a C=C double bond, hydration of alkenes to alcohols, esterification (acid + alcohol → ester + water, using concentrated H₂SO₄ catalyst), and oxidation of primary alcohols to aldehydes and then to carboxylic acids. For condensation polymerisation, know both nylon (polyamide) and terylene (polyester) formation. Ion test questions require precise recall of specific reagents and observations. Know the complete set of flame test colours (Li: crimson, Na: yellow, K: lilac, Ca: brick red, Ba: apple green), precipitate colours for metal hydroxides with NaOH (Cu²⁺: blue, Fe²⁺: green, Fe³⁺: orange/brown), and the tests for chloride (AgNO₃ → white precipitate), sulfate (Ba²⁺ → white precipitate), and carbonate (acid → CO₂ fizzing).