According to Beer-Lambert law the absorption of light by a solution is directly proportional to the concentration of that solution.
Mathmatically,
A = ∈ C l ------- (1)
Where,
A = Absorption = 1.23
∈ = molar absorptivity coefficient = 6460 M⁻¹cm⁻¹
C = Concentration = ?
l = Path Length = 1 cm
Solving eq.1 for concentration,
C = A / ∈ l
Putting values,
C = 1.23 / (6460 M⁻¹cm⁻¹ × 1 cm)
C = 0.00019 mol/L
