Question

A titration of 50.00 mL of a solution containing iodide is titrated to a thiocyante endpoint with 0.0683 M silver nitrate solution. The initial buret reading was 1.26 mL. At the first evidence of the red endpoint, the buret read 13.89 mL. Find the concentration of the iodide in the original solution. Express the final result also as a percentage (w/v) of calcium iodide in the solution.