The solubility product constant, \(K_{\text{sp}}\), is defined by the solubility \(S\) using the equation: \[
K_{\text{sp}} = S^2
\] With a solubility \(S = 1.1 \times 10^{-5}\) mol/L, the solubility product constant is calculated as: \[
K_{\text{sp}} = (1.1 \times 10^{-5})^2 = 1.21 \times 10^{-10}
\]