Question

What species is responsible for the observed colour change when KSCN(aq) and Fe(NO3)3(aq) aremixed?

Answer 1

Step-by-step explanation:

When KSCN is mixed with Fe(NO₃)₃ in solution, an equilibrium of mixture of Fe³⁺, SCN⁻ and FeSCN²⁺ is produced.

Fe(NO₃)₃ (aq) ----> Fe³⁺ (aq) + 3 NO₃⁻ (aq)

KSCN (aq) ----> K⁺ (aq) + SCN⁻ (aq)

Fe³⁺ (aq) + SCN⁻ (aq) <-----> FeSCN²⁺

Yellow + Colourless <----> Red

FeSCN²⁺ will be responsible for the red colour.

Answer: FeSCN²⁺