CSET Science: Chemistry case studies
CSET Science: Chemistry · Put your knowledge to work in context.
CSET: Science is one of the California Subject Examinations for Teachers, the assessment family the California Educator Credentialing Examinations site describes as covering California educator credentialing assessments. Candidates seeking a single subject teaching credential in science take it to demonstrate subject-matter competence; the chemistry option is aimed at candidates who intend to teach chemistry at the secondary level, and at candidates adding science to an existing authorization. The CSET Science: Chemistry case studies are 5 cases and about 3,989 words.
1Percent Yield in a Lead(II) Iodide Precipitation
During a precipitation lab, a group is asked to prepare lead(II) iodide and report a percent yield. They pipet 25.0 mL of 0.200 M Pb(NO3)2 into a beaker and add 30.0 mL of 0.150 M KI with stirring; a yellow solid forms at once.
811 words, about 4 min2Hydrogen Collected over Water: Vapor Pressure and Real-Gas Reasoning
A group reacts mossy zinc with excess 3 M HCl and collects the hydrogen over water in an inverted graduated cylinder. When bubbling stops they adjust the cylinder so the water level inside matches the level in the beaker, then read 42.5 mL at 22.0 °C with a barometer reading of 748 mmHg.
784 words, about 4 min3N2O4 Dissociation: Incomplete Equilibration and Temperature Effects
A sealed, rigid 1.00 L flask is charged with dinitrogen tetroxide to an initial pressure of 0.100 atm at 298 K. Thirty seconds later, when the gas has turned pale brown, the gauge reads 0.132 atm.
786 words, about 4 min4Galvanic Cell Voltage Below the Nernst Prediction
Students assemble a galvanic cell from a copper strip in 0.0010 M Cu(NO3)2 and a silver strip in 1.00 M AgNO3, joined by a KNO3 agar salt bridge, and read 0.50 V on a digital voltmeter at 25 °C. One group predicts 0.46 V by subtracting the tabulated standard potentials; a second group predicts -0.46 V "because electrons flow from silver to copper." The silver strip was polished, but that beaker had last held a chloride solution and was rinsed only with tap water.
767 words, about 4 min5Choosing a Rate Law and Judging a Proposed Mechanism
Students follow the reaction A + B → products at 25.0 °C by absorbance and record initial rates. Run 1 uses [A]0 = 0.100 M and [B]0 = 0.100 M and gives 2.0 × 10^-4 M/s.
841 words, about 4 min