Ca²⁺ + EDTA⁴⁻ ⇌ CaEDTA²⁻
The equilibrium constant for this reaction is very large, indicating that the reaction proceeds almost to completion. This means that nearly all of the calcium ions in a solution will be complexed with EDTA if enough EDTA is present.
The complexation of calcium by EDTA is important in many biological and industrial applications. For example, EDTA is used as a chelating agent to remove calcium ions from water, and it is also used in medicine to treat conditions such as hypercalcemia (high levels of calcium in the blood).
