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ChemBench
The foundation of UV-Vis spectrophotometry — how much light a solution absorbs tells you its concentration.
Beer-Lambert's law (A = εcl) says absorbance is proportional to concentration and path length — this linear relationship is why spectrophotometers can measure unknown concentrations by comparing absorbance to a calibration curve of known standards.
At high concentrations, molecular interactions (aggregation, refractive index changes) cause deviations from linearity — this is why spectrophotometry is most reliable for dilute solutions, typically below 1–2 absorbance units.
Molar mass of any chemical formula (e.g. H2O, C6H12O6, Ca(OH)2).
OpenPercent composition of an element within a chemical formula.
OpenSimplest whole-number ratio formula from elemental masses or percentages.
OpenPercent yield from actual and theoretical reaction yields.
OpenAbsorbance (A)
2.6
What you entered
A = ε × c × l
6500 × 0.0004 × 1= 2.6Transmittance = 10^(−A) × 100
10^(−2.6) × 100= 0.2512%Result
Absorbance (A): 2.6
With ε = 6500, c = 0.0004 mol/L, and l = 1 cm, the absorbance is 2.6 and transmittance is 0.25%.