The action of an alkaline I2 solution on the rodenticide warfarin, C19H16O4 (308.34 g/mol), results in the formation of 1 mol of iodoform, CHI3 (393.73 g/mol) for each mole of the parent compound reacted. Analysis of warfarin can then be based on the reaction between CHI3 and Ag 1+:
The CHI3 produced from a 13.96-g sample was treated with 25.00 mL of 0.02979 M AgNO3, and the excess Ag 1+ was then titrated with 2.85 mL of 0.05411 M KSCN. Calculate the percentage of warfarin i the sample.