Answer to Question #173348 in Chemistry for Kayla Williams

Question

An aqueous solution containing iron (II) (Fe²⁺) at a concentration of 2.5 x 10^-3 mg cm^-3 is subjected to the above treatment and measures an absorbance of 0.524. A water sample of unknown iron (II) (Fe²⁺) concentration is similarly treated and measures an absorbance of 0.350. Calculate the concentration of iron (II) (Fe²⁺) in the unknown sample in mg cm^-3.

Answer 1

According to the equation:

A = ecl

where e - molar absorption coefficient, c - concentration, l - optical path length, A - absorbance.

As molar absorption coefficient and optical path length are the same for both solutions, the concentration equals:

C₂ = A₂ / el = A₂ × C₁ / A₁ = 0.350 × 2.5 x 10^-3 mg cm^-3 / 0.524 = 1.7 × 10^-3 mg cm^-3

Answer: 1.7 × 10^-3 mg cm^-3