why must MgCl2.6H20 be added to the EDTA solution
Who knows? It depends upon what procedure you're following. What is the context of the problem. Probably you're talking about the determination of a metal, say calcium or zinc or another and MgCl2 must be added in order to complex an interfering metal. You need to clean up the problem in order for us to know what's going on.
MgCl2.6H2O (magnesium chloride hexahydrate) is typically added to an EDTA (ethylenediaminetetraacetic acid) solution for a process called complexometric titration. This process is commonly used to determine the concentration of metal ions in a solution.
The purpose of adding MgCl2.6H2O to the EDTA solution is to provide a source of magnesium ions (Mg2+). These Mg2+ ions act as masking agents to prevent interference from other metal ions during the titration process.
Here's an explanation of how it works:
1. Complexation reaction: EDTA has a high affinity for metal ions and readily forms strong complexes with them. When EDTA reacts with a metal ion, it forms a stable metal-EDTA complex. In the absence of masking agents, other metal ions in the solution might also react with EDTA, leading to erroneous results.
2. Masking effect: By adding MgCl2.6H2O to the EDTA solution, the magnesium ions preferentially react with any interfering metal ions in the solution before they can react with EDTA. This selective binding of interfering metal ions by the magnesium ions is known as the masking effect. It ensures that only the targeted metal ion, which is being titrated, reacts with EDTA.
3. Formation of stable complexes: Magnesium ions form less stable complexes with EDTA compared to other metal ions. Therefore, once all the interfering metal ions have reacted with the magnesium ions, the remaining EDTA in the solution can effectively react with the targeted metal ion to form a stable metal-EDTA complex. This complex can be easily detected and the concentration of the metal ion can be determined.
Overall, the addition of MgCl2.6H2O to the EDTA solution helps to eliminate the interference of other metal ions, ensuring accurate and precise determination of the concentration of the metal ion being analyzed.
MgCl2.6H2O, also known as magnesium chloride hexahydrate, is added to the EDTA solution for several reasons:
1. pH Buffering: Magnesium chloride helps to maintain a specific pH range in the solution. The addition of magnesium chloride helps to prevent the pH from drastically changing during the titration process.
2. Masking Effect: In some cases, the presence of certain metal ions can interfere with the titration process. Magnesium chloride helps to mask or inhibit the interference of these metal ions, allowing for more accurate and reliable results.
3. Complex Formation: Magnesium chloride participates in the formation of chelate complexes with EDTA. These complexes increase the stability and solubility of the EDTA, making it more effective in its function as a chelating agent.
Overall, adding magnesium chloride to the EDTA solution ensures proper pH buffering, minimizes interference from other metal ions, and enhances the formation of chelate complexes, leading to better accuracy and precision in EDTA titrations.