Question

A series of solutions of CoCl2 was prepared.
Solution 1 = 5.0 mL CoCl2, O mL water. Absorbance = 0.778, %T = 16.7, path length = 1.17 cm.
Solution 2 = 4.0 mL CoCl2, 1.0 mL water. Absorbance = 0.640, %T = 22.9, path length = 1.17 cm.
Calculate the concentration of Co2+= at 500 nm.