Q1(c). Molar absorptivity from the transmittance

Answer in brief

A = −log T = 0.2218, so ε = A/bc = 221.8 ≈ 222 L mol⁻¹ cm⁻¹.

Key points

• Beer–Lambert law: A = εbc = −log T.
• A = −log(0.60) = 0.2218.
• ε = A/bc = 0.2218/(1 cm × 1 × 10⁻³ mol L⁻¹) = 221.8 ≈ 222 L mol⁻¹ cm⁻¹.
• Check: at double the concentration A = 0.4436 and T = 0.36; A doubles, T does not halve.