NSEC case studies
NSEC · Put your knowledge to work in context.
The National Standard Examination in Chemistry (NSEC) is the chemistry paper of the National Standard Examination (NSE) conducted by the Indian Association of Physics Teachers (IAPT). It is the entry step towards the international science olympiads, and IAPT describes the NSE as the "First Step Towards INTERNATIONAL SCIENCE OLYMPIADS". The NSEC case studies are 5 cases and about 4,807 words.
1A Sealed N2O4/NO2 Flask: Whose Pressure Bookkeeping Is Right?
A sealed 2.00 L glass flask at 320 K is charged with 0.0200 mol of pure N2O4 and nothing else, then left until the colour stops deepening. The total pressure at that point is measured as 0.400 bar.
830 words, about 4 min2A Copper–Silver Cell That Reads 0.28 V Instead of 0.34 V
A student assembles the cell Cu(s) Cu2+(aq, 0.010 mol L^-1) Ag+(aq, 0.0010 mol L^-1) Ag(s) at 298 K, using E°(Ag+/Ag) = +0.80 V and E°(Cu2+/Cu) = +0.34 V. A high-impedance digital voltmeter reads 0.28 V, reproducibly, on three freshly made cells.
918 words, about 5 min3Three NMR Signals and a Formula: Ethyl Acetate or Methyl Propanoate?
A colourless neutral liquid X, molecular formula C4H8O2, boils at 77 °C, is insoluble in water, miscible with ether, and gives no effervescence with aqueous sodium hydrogen carbonate. Its IR spectrum shows a strong sharp band at 1740 cm^-1, no absorption between 2500 and 3300 cm^-1, and nothing in the 3300–3600 cm^-1 region.
946 words, about 5 min4A Magnetic Moment of 2.3 BM That Does Not Correspond to Any Whole Number of Electrons
Two iron(III) samples sit on the bench: deep red K3[Fe(CN)6] and very pale violet Fe(H2O)63. Both contain octahedral Fe(III).
998 words, about 5 min5Five Kinetic Runs, One of Which Does Not Belong
Rate data for A + B → products were collected at 298 K in a thermostatted bath, with initial rates measured by stopped-flow spectrophotometry immediately after mixing. Concentrations are in mol L^-1 and rates in mol L^-1 s^-1.
1,115 words, about 6 min