A pigment suspected of being contaminated with arsenic is treated to convert any arsenic present into a solution of arsenic acid. The solution is then treated with an excess of silver nitrate and a small amount of solid is observed. The solid is collected and then dissolved in an excess of dilute nitric acid to release the silver ion present. The solution is finally diluted to 250.0mL. A 25.00mL aliquot is titrated with 0.003510M potassium thiocyanate solution using iron (III) as an indicator, 14.83mLs being required.
What should be the concentration of the potassium thiocyanate solution in order that each mL of solution correspond to exactly 1 mg of arsenic present?