{"knowledge_schema": {"broad_category": "Chemistry \u2192 Coordination Chemistry \u2192 Complex Ion Equilibria", "refinement": "This problem involves the dissociation of a metal complex in solution and the calculation of ion concentrations based on equilibrium constants.", "specific_scope": "The focus is on determining the concentration of calcium ions in a solution containing a known concentration of the Ca-EDTA complex, using the stability constant (K) for the complex.", "goal": "Calculate the concentration of free calcium ions in the solution based on the provided concentration of the complex and the stability constant."}, "summary": "This problem pertains to coordination chemistry, specifically the behavior of metal complexes in solution. It requires understanding the dissociation of the Ca-EDTA complex and applying the stability constant to find the concentration of free calcium ions. Given the concentration of the complex and the stability constant, the goal is to calculate the concentration of calcium ions in the solution, which is found to be 6.3x10^-7 M."}