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CSEC Chemistry study materials
CSEC Chemistry study resources

CSEC Chemistry cheat sheet

CSEC Chemistry · Keep the key ideas within reach.

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Chemistry Content and Principles (CSEC Chemistry Syllabus)

  • Mole concept: n = m/M; at STP (273 K, 1 atm) one mole of any gas occupies 22.4 dm³; molar volume is used to convert gas volume to moles before applying reaction stoichiometry.

  • Avogadro constant N_A = 6.02 × 10²³ mol⁻¹; number of particles = n × N_A; concentration c = n/V with V in dm³, so 250 cm³ = 0.250 dm³.

  • Stoichiometry decision rule: balance the equation first, convert all given quantities to moles, divide by the stoichiometric coefficients to find the limiting reagent, then scale to the required product.

  • Acids and bases: Arrhenius/Brønsted–Lowry definitions; strong acids (HCl, HNO₃, H₂SO₄) ionise completely, weak acids (CH₃COOH, H₂CO₃) partially; pH = −log₁₀[H⁺], and neutral aqueous pH = 7 at 25 °C.

  • Neutralisation: acid + base → salt + water; titration calculation uses c₁V₁/c₂V₂ = coefficient ratio from the balanced equation; indicators change over a characteristic pH range (phenolphthalein 8.3–10.0, methyl orange 3.1–4.4).

  • Redox: oxidation is loss of electrons/increase in oxidation number, reduction is gain/decrease; oxidising agent is itself reduced. Oxidation numbers: free element 0, simple ion = charge, oxygen usually −2, hydrogen usually +1.

  • Electrolysis: cathode attracts cations and is the site of reduction; anode attracts anions and is the site of oxidation; in electrolysis the anode is positive, in a cell the anode is negative. Products depend on relative discharge (reactivity) series.

  • Bonding rules: ionic = metal + non-metal with large electronegativity difference (high m.p., conducts when molten/aqueous); covalent = shared electron pairs (usually low m.p., non-conducting); metallic = delocalised electrons (conducts in solid and liquid).

  • Rates and equilibrium: rate increases with concentration, temperature, surface area and catalyst; Le Chatelier's principle - a system at equilibrium shifts to oppose the imposed change (concentration, pressure, temperature).

  • Organic families: alkanes CₙH₂ₙ₊₂ (substitution, saturated); alkenes CₙH₂ₙ (addition, decolourises bromine water); alcohols CₙH₂ₙ₊₁OH (oxidation to aldehyde/acid); carboxylic acids (esterification with alcohols, pH < 7).