Q4(a). Absorbance of an unbuffered indicator solution at 430 nm

The equilibrium constant for the given conjugate acid–base pair is 2.5 × 10⁻⁵: HIn + H₂O ⇌ In⁻ + H₃O⁺. Determine the absorbance at 430 nm for the concentration of HIn = 3.0 × 10⁻⁴ M (up to 3 decimal places), using the following data: HIn, absorption maximum 430 nm, molar absorptivity 4.0 × 10³ at 430 nm and 7.25 × 10² at 600 nm; In⁻, absorption maximum 600 nm, molar absorptivity 3.0 × 10² at 430 nm and 9.65 × 10³ at 600 nm. Given: path length of the cuvette = 1 cm; molar absorptivity in M⁻¹ cm⁻¹.