Question

Calculate the concentration of Fe^3+ present in the standard solutions . Given information: Stock solutions: I: 60 ml of Fe(NO3)3 0.20 M in 0.50 M HNO3 (used to make standard solutions) II. 70 ml of Fe(NO3)3 2.0x10^-3M in 0.50 M HNO3 (used to make equilibrium solutions) III. 40 ml KSCN 2.0x10^-3 M in 0.50 M HNO3 (used to make both standard and equilibrium solutions) IV. 100 ml HNO3 0.50M (used as solvent for all solutions) 4 standard solutions 100 ml each with varying concentrations of KSCN Standard solutions:[SCN^-] A. 1.5x10^-4 M B. 1.0x10^-4 M C. 5.0x10^-5 M D. 2.0x10^-5 M what are the concentration of [Fe^3+] in the standard solutions.

Answer 1

Again you. This time the significant information (50 mL from solution I is transfered in each 100 mL standard solution) is missing. Nobody can find an answer here. But you have the answer from me in a previous answer.

Maybe you forget that, in standards A-D, Fe3+ is in high excess. In this solution you have variable concentration of [FeSCN]2+ complex. SCN- is complete reacted, because FE3+ is in high excess. The concentration of the complex ion is equal with the concentration of SCN- (written in your table).