Grade 12 Physical Sciences Past Papers

Organic Chemistry is one of the most content-rich sections of NSC Physical Sciences Paper 2. Under the CAPS curriculum, Grade 12 learners must master IUPAC Nomenclature for naming and drawing all major functional groups: alkanes, alkenes, alkynes, haloalkanes, alcohols, aldehydes, ketones, carboxylic acids, and esters. Correct naming — including chain length, substituent position, and functional-group suffix — carries significant mark allocation in NSC Paper 2.

Isomers — chain, positional, and functional isomers — are tested annually. Learners must identify structural isomers from a molecular formula and draw every valid isomer for small organic molecules. A common CAPS examination task is to draw all alcohols or haloalkanes with the formula C₄H₉OH and name each using IUPAC rules.

The physical properties of organic compounds — particularly boiling points and melting points — are directly determined by Intermolecular Forces. Stronger IMFs (hydrogen bonding > dipole-dipole > London dispersion forces) produce higher boiling points. CAPS examiners regularly ask learners to compare boiling points across a homologous series, between structural isomers, or between compounds with different functional groups — making this one of the highest-yield topics in Paper 2.

Chemical Equilibrium is one of the most conceptually demanding topics in Grade 12 CAPS Chemistry. At equilibrium, the forward and reverse reaction rates are equal and macroscopic concentrations remain constant — but the system is dynamic, not static. The equilibrium constant K_c is defined as the ratio of molar product concentrations to molar reactant concentrations, each raised to the power of its stoichiometric coefficient. Writing the correct K_c expression — and calculating its value from equilibrium concentrations — is a core NSC Paper 2 skill.

Le Chatelier's Principle governs how a system at equilibrium responds to disturbance: changes in concentration, temperature, or pressure (for gaseous reactions) cause the equilibrium position to shift in the direction that minimises the disturbance. CAPS Paper 2 examiners test learners' ability to predict the direction of shift, explain the effect on reactant and product concentrations, and critically — to identify whether K_c itself changes. Only a temperature change alters the value of K_c; changes in concentration or pressure shift the position of equilibrium without changing K_c.

Electrochemical Cells is a high-value section of NSC Chemistry Paper 2. A Galvanic (voltaic) cell converts chemical energy to electrical energy through a spontaneous redox reaction. Learners must correctly identify the anode (where oxidation occurs) and cathode (where reduction occurs), write balanced half-reactions, and calculate the standard cell potential using the CAPS Standard Electrode Potential table: E°_cell = E°_cathode − E°_anode. A positive E°_cell indicates a spontaneous reaction.

Electrolytic cells, by contrast, use an external electrical energy source to drive a non-spontaneous reaction. CAPS learners must clearly distinguish between the two cell types, predict the products at each electrode, and explain industrial applications such as electroplating and the chloralkali process. A common NSC Paper 2 question asks learners to identify which species is oxidised and which is reduced using the Standard Electrode Potential table provided in the NSC data booklet — and to justify the spontaneity of the overall reaction.