Assam ASSEB HS Chemistry case studies
Assam ASSEB HS Chemistry · Put your knowledge to work in context.
ASSEB HS Chemistry is the Class XII chemistry examination set by the Assam State School Education Board, the body constituted in 2024 that took over the higher-secondary examination functions previously handled by AHSEC. Students in Assam's HS second year sit it as their school-leaving chemistry credential: the result feeds directly into degree admission, and the syllabus overlaps heavily with what engineering and medical entrance tests assume you already know. The Assam ASSEB HS Chemistry case studies are 5 cases and about 3,555 words.
1Copper–steel joint in a water line: which metal corrodes, and will one 50 g zinc block do?
A municipal water-supply line in Guwahati carries groundwater (25 °C, pH 6.5, [Fe2+] ≈ 1.0 × 10−3 mol L−1, air-saturated) through a mild-steel pipe joined to a copper fitting. After eight months the iron wall beside the joint shows deep pitting, while the copper surface remains bright.
724 words, about 4 min2Half-life data at two temperatures: can a 12-minute reactor meet the 90% specification?
A buffered aqueous intermediate decomposes in a plug-flow reactor. Its half-life is 69.3 min at 300 K and does not change when the initial concentration is raised from 0.020 mol L−1 to 0.080 mol L−1.
672 words, about 3 min3Three chromium(III) chloride hydrates: AgCl titres, conductance and a magnetic proposal that cannot work
Three samples labelled A, B and C all analyse to the same formula, CrCl3·6H2O, but differ in colour (violet, blue-green and dark green) and in behaviour towards silver nitrate. For each, a 0.0100 mol sample is dissolved in cold water and treated with excess AgNO3: A gives 0.0300 mol AgCl, B gives 0.0200 mol and C gives 0.0100 mol.
718 words, about 4 min4Separating phenol, benzyl alcohol and anisole - and two Williamson proposals that will not both work
A 15.0 g mixture of phenol, benzyl alcohol and anisole (roughly equal masses) must be separated and each component identified using only: 10% NaOH, dilute HCl, neutral FeCl3 solution, bromine water, Lucas reagent (ZnCl2 in conc. HCl) and a fractional distillation set-up with a 20 cm column.
739 words, about 4 min5Mohr's salt titration: a 96% figure that hides two procedural mistakes
0.980 g of Mohr's salt, FeSO4·(NH4)2SO4·6H2O (M = 392 g mol−1), is dissolved in dilute H2SO4 and made up to 100.0 mL; part of the Fe2+ has been air-oxidised to Fe3+. Three 25.0 mL portions are titrated with 0.0200 mol L−1 KMnO4, giving concordant burette readings of 6.00 mL.
702 words, about 4 min