NSSCAS Chemistry (8224) case studies
NSSCAS Chemistry (8224) · Put your knowledge to work in context.
The NSSCAS Chemistry (8224) is the Advanced Subsidiary level chemistry qualification taken in Namibia, typically in the first year of senior secondary study after the NSSCO phase. It suits learners who intend to continue to NSSCAS/NSSCAL science or move into tertiary science, health, engineering, mining, agriculture or laboratory work, and it also serves as evidence of post-compulsory science competence for employers and admissions officers. The NSSCAS Chemistry (8224) case studies are 5 cases and about 3,198 words.
1Limiting reagent and crystal yield in copper(II) sulfate preparation
A technician must prepare copper(II) sulfate-5-water crystals from copper(II) oxide and 1.50 mol dm−3 sulfuric acid. The stock bottle contains 25.0 cm3 of acid, and 2.00 g of copper(II) oxide is available (Mr = 79.5).
516 words, about 3 min2Thiosulfate clock reaction: judging first-order behaviour
A student investigates the rate of reaction between sodium thiosulfate and dilute hydrochloric acid by timing how long a black cross takes to disappear. Each run uses 50.0 cm3 total volume made by mixing thiosulfate solution with water and then 5.0 cm3 acid.
593 words, about 3 min3Purifying ethyl ethanoate from a crude esterification mixture
A student prepares ethyl ethanoate by refluxing ethanol with ethanoic acid and a few drops of concentrated sulfuric acid. The crude distillate is cloudy, has a strong fruity smell, and turns blue litmus red.
705 words, about 4 min4Copper electrodes versus platinum electrodes in copper(II) sulfate electrolysis
A student electrolyses 100 cm3 of 0.500 mol dm−3 copper(II) sulfate solution using two copper electrodes. The current is held at an average of 0.500 A for 30.0 minutes; the ammeter fluctuates by about ±0.02 A.
639 words, about 3 min5Identifying group 2 carbonates and judging thermal safety
A technician has three unlabelled white solids: magnesium carbonate, calcium carbonate and barium carbonate. They are in a damp cupboard, and the labels have fallen off.
745 words, about 4 min