ORT Chemistry case studies
ORT Chemistry · Put your knowledge to work in context.
ORT Chemistry is a subject examination in chemistry used in the ORT (Общественный республиканский тест) assessment system, a standardized testing framework administered in Kyrgyzstan and used for admission and placement decisions at some institutions. This page is an independent study resource: it is not affiliated with, endorsed by, or produced by the testing body, and candidates should always confirm the current official specification before registering. The ORT Chemistry case studies are 5 cases and about 2,402 words.
1Buffer recipe check before pH-meter calibration
A school laboratory needs 250.0 mL of a pH 4.75 buffer to calibrate a newly purchased pH meter before a practical examination. The stock cupboard contains 0.200 M acetic acid (pKa = 4.76) and solid sodium acetate trihydrate, CH3COONa·3H2O (M = 136.1 g/mol).
491 words, about 2 min2Double titration of a carbonated NaOH/Na2CO3 powder
A forensic-style practical receives 1.500 g of a white powder known to contain sodium hydroxide, sodium carbonate, and sodium chloride only. The powder has been stored in a loosely capped bottle in a damp store room, so some hydroxide may have carbonated.
528 words, about 3 min3Copper plating a steel key: calculation and deposit quality
In a school electroplating project, a steel key of total surface area 18.0 cm2 is to be copper-plated from an acid copper sulfate bath (CuSO4 plus dilute H2SO4). The group uses a copper anode and a current of 0.500 A for 40.0 min.
445 words, about 2 min4Fischer esterification: equilibrium, yield and scale-up
In a pre-university synthesis project, a student refluxes 23.0 g of ethanol (0.500 mol) with 30.0 g of glacial acetic acid (0.500 mol) and 1.0 mL of concentrated sulfuric acid. After 1 hour the mixture is cooled, diluted, and titrated: 0.200 mol of acetic acid remains.
442 words, about 2 min5Qualitative cation mixture and heavy-metal waste
A school club is given a clear, acidic unknown solution labelled 'Mixture 4'. The label states that it contains exactly two cations chosen from Pb2+, Ba2+, Cu2+, and Fe3+, each at about 0.05 M in 0.5 M HNO3.
496 words, about 2 min