Fe3+(aq) + KSCN(s) → FeSCN2+(aq) + K+(aq) 5. To determine the moles of Fe3+(aq) in a 100. mL sample — Solutions Chemistry Question

Fe³⁺(aq) + KSCN(s) → FeSCN²⁺(aq) + K⁺(aq)

1. To determine the moles of Fe³⁺(aq) in a 100. mL sample of an unknown solution, excess KSCN(s) is added to convert all the Fe³⁺(aq) into the dark red species FeSCN²⁺(aq), as represented by the equation above. The absorbance of FeSCN²⁺(aq) at different concentrations is shown in the graph below.

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If the absorbance of the mixture is 0.20 at 453 nm, how many moles of Fe³⁺(aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) is negligible.)