18. Solving a chemistry problem

2. An excess of reagent was added to a 20.0 cm3 aliquot of a solution containing 5.0 mg/l Al(III) and diluted to 50 ml. What is the optical density of the resulting solution, measured at 580 nm in a 10 mm cuvette. The molar absorption coefficient of the aluminum complex is 6000 l/(mol*cm).