TASC Chemistry Level 4 case studies
TASC Chemistry Level 4 · Put your knowledge to work in context.
Chemistry Level 4, listed by the Tasmanian course code CHM415115, is a senior secondary chemistry course within the TASC system - the body that sets and quality-assures senior secondary courses and external assessments in Tasmania. This page is an independent study resource. It is not affiliated with, endorsed by, or produced by TASC, and nothing here should be read as an official statement of course requirements. An important caveat shapes everything below. The TASC Chemistry Level 4 case studies are 5 cases and about 2,443 words.
1Buffer Capacity at the Edge
A first-year lab group prepares 1.00 L of an ethanoate buffer containing 0.100 mol CH3COOH (pKa = 4.76) and 0.050 mol CH3COONa. Their freshly calibrated pH meter reads 4.44 at 25 °C, while the Henderson–Hasselbalch (HH) prediction is 4.46.
506 words, about 3 min2The Run That Did Not Fit
Students study the peroxodisulfate–iodide clock reaction at 25 °C: S2O8^2− + 2I− → 2SO4^2− + I2. Each run contains 0.0050 mol L−1 thiosulfate and starch, so 0.0025 mol L−1 peroxodisulfate has been consumed when the blue colour appears.
526 words, about 3 min3The Flyer and the Word 'Chemical'
A residents' group drafts a flyer: 'Our town's water contains 0.06 mg/L of chloroform, a cancer-linked chemical, so it is unsafe. The pH is 8.1, which is alkaline and therefore healthier.
491 words, about 2 min4Choosing a Disinfection Strategy
A village of 600 people uses a borehole. Turbidity is normally 0.3 NTU but rises to 8 NTU for 2–3 days after storms, several times a year.
472 words, about 2 min5The Indicator Mismatch
A student titrates 25.0 mL of 0.100 mol L−1 ethanoic acid (Ka = 1.8 × 10^−5) with 0.100 mol L−1 NaOH. Using methyl orange (colour change pH 3.1–4.4), the student stops at the first orange tint and records 24.8 mL.
448 words, about 2 min