A reaction mixture initially contains [Fe³⁺] = 2.4 × 10⁻⁴ mol L⁻¹ and [SCN⁻] = 8.0 × 10⁻⁴ mol L⁻¹. Then, the following chemical equilibrium is established: Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq). At equilibrium, [FeSCN²⁺] = 1.7 × 10⁻⁴ mol L⁻¹. Calculate the value of the unitless equilibrium constant.
a) 3.9 × 10³
b) 8.9 × 10²
c) 1.1 × 10⁻³
d) 2.6 × 10⁻⁴
e) 7.5 × 10⁻¹²