Test students' ability to apply the Beer-Lambert law to compute unknown solution concentrations from UV-Vis absorbance measurements. Scope: use A = ε·l·c with provided molar absorptivity (ε) and path length (l), perform unit conversions and dilution-factor corrections, construct or use a simple calibration (single-point or multi-point) to determine concentration, and identify common causes of deviation from linearity (high absorbance, scattering, chemical equilibria) that limit direct application.