WACE Chemistry ATAR case studies
WACE Chemistry ATAR · Put your knowledge to work in context.
The WACE Chemistry ATAR is the Western Australian senior secondary course and external examination that produces a chemistry score for university admission. It suits students who intend to study chemistry, pharmacy, medicine, engineering, environmental science or related fields, and who are prepared to combine conceptual understanding with quantitative problem solving. The course moves through atomic structure and the periodic table, bonding and molecular shape, the mole concept and stoichiometry, acids and bases, redox and electrochemistry, thermochemistry, reaction rates and equilibrium, organic functional groups, and laboratory analysis skills. Assessment blends school-based practical investigations and tests with an externally set written paper that includes multiple choice, short answer, extended response, and practical or data-analysis items. The WACE Chemistry ATAR case studies are 5 cases and about 2,612 words.
1Identifying an Unknown Group 2 Carbonate
A student is given an unlabelled bottle of a white solid, suspected to be a Group 2 carbonate, MCO3. To identify the metal, 1.250 g of the solid is reacted completely with excess dilute hydrochloric acid, and the carbon dioxide evolved is collected over water.
582 words, about 3 min2Bond Polarity, Shape and Boiling Point in a Series of Molecules
A student compares four substances: CH4, NH3, H2O and HF. All have small molecules with hydrogen bonded to a non-metal, yet their boiling points differ markedly: CH4 −162 °C, NH3 −33 °C, HF 20 °C, H2O 100 °C.
536 words, about 3 min3Titration Decision: Which Indicator and Is the Result Trustworthy?
A student titrates 25.00 mL of an unknown weak monoprotic acid, HA, against 0.100 mol/L NaOH. Phenolphthalein (colour change pH 8.2–10.0) is used.
484 words, about 2 min4Electrolysis of Brine: Competing Reactions and Product Prediction
A student electrolyses concentrated aqueous sodium chloride using inert graphite electrodes. At the cathode, a gas is evolved and the surrounding solution becomes alkaline.
512 words, about 3 min5Equilibrium Shift on Heating: Interpreting Colour and Yield Data
A sealed flask contains the equilibrium mixture 2NO2(g) ⇌ N2O4(g), which is brown (NO2) and colourless (N2O4). The forward reaction is exothermic, ΔH = −57 kJ/mol.
498 words, about 2 min