Paper: CSIR-NET December 2011 · Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Chemical Kinetics – General · Marks: 2 · Difficulty: Medium
Using cuvettes of $0.5\,\mathrm{cm}$ path length, a $10^{-4}\,\mathrm{M}$ solution of a chromophore shows $50\%$ transmittance at certain wave length. The molar extinction coefficient of the chromophore at this wave length is $(\log 2=0.301)$
(a)$1500\,\mathrm{M^{-1}\,cm^{-1}}$
(b)$3010\,\mathrm{M^{-1}\,cm^{-1}}$
(c)$5000\,\mathrm{M^{-1}\,cm^{-1}}$
(d)$6020\,\mathrm{M^{-1}\,cm^{-1}}$
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
A = log(1/0.5) = 0.301 = ε × 0.5 cm × 10⁻⁴ M, so ε = 6020 M⁻¹ cm⁻¹ (d).