To determine this calibration curve, solutions of 2.000 mM KSCN and 0.1995 (~0.2) M Fe(NO₃)₃ were prepared with the initial materials. First, 1.00 mL of the Fe(NO₃)₃ and 2.00 mL of the KSCN solution were mixed and diluted in a 10.00 mL volumetric flask. The cuvette was placed into a Vernier Spectrophotometer (Go Direct® SpectroVis® Plus Spectrophotometer) and absorbance was plotted against wavelength. The wavelength of maximum absorbance was determined to be 446.8 nm and would function as a reference to compare the absorbance values of varying concentrations of the ferric thiocyanate solutions. Four more solutions were prepared using varying concentrations of KSCN and were placed in the spectrophotometer. The absorbance values of these solutions at a wavelength of 446.8 nm were measured and recorded. The final concentration of FeSCN 2+ was assumed to be equal to the initial concentration of KSCN since the large excess of Fe(NO₃)₃ allows for the complexation reaction to essentially go to completion, removing all of the SCN -.