CuS(s) ⇄ Cu₂⁺ (aq) + S₂⁻ (aq) Ksp = 6.0 x 10⁻³⁷

Cu₂⁺(aq) + 4CN⁻ (aq) ⇄ Cu(CN)₄²⁻ (aq) Kf = 1.0 x 10²⁵

When CN⁻ is added to CuS(s), a combination of these reactions occurs

CuS(s) + 4CN⁻ (aq) ⇄ Cu(CN)₄²⁻ (aq) + S₂⁻ (aq)

What mass of CuS (95.6 g/mol) can dissolve in 66.5 L of 5.1 M KCN solution?