burettes x 3
100 cm3 volumetric flasks x 7 (or use one, thoroughly washing it between samples)
colorimeter and suitable filter (blue) - a solution of the complex displays maximum absorption at 480 nm
potassium thiocyanate containing 250 mg dm−3 thiocyanate (250 ppm) (30 cm3)
iron(III) chloride solution 0.41 mol d−3 (70 cm3)
solution of unknown thiocyanate concentration (10 cm3)