How to Calculate Spectrophotometry
What is Spectrophotometry?
Spectrophotometry measures light absorption: A = log(I₀/I) = εbc (Beer-Lambert law), used for quantitative analysis.
Step-by-Step Guide
- 1Input measured absorbance, path length, molar absorptivity
- 2Calculate concentration
- 3Generate calibration curve if multiple samples
Worked Examples
Input
Absorbance 0.5, ε = 5000 M⁻¹cm⁻¹, b = 1 cm
Result
c = A/(εb) = 0.5/5000 = 1×10⁻⁴ M
Common Mistakes to Avoid
- ✕Using wrong wavelength for compound
- ✕Not accounting for baseline absorbance
Frequently Asked Questions
What's molar absorptivity?
Characteristic of molecule at specific wavelength; tabulated values for known compounds.
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