Dear Sir. Concerning your issue about the titration of Zinc Oxide in Calamine Lotion by complexometric titration. complexometric or chelometric titration because the titrant, a ligand, reacts with the analyte, a metal ion, to form a complex, more specifically a chelate in this case. A chelate is a ligand that has two or more sites that bind to the central ion. EDTA [ethylenediaminetetraacteic acid, C10H16N2O8, (HOOCCH2)2N-CH2CH2-N(CH2COOH)2, MM = 292.24 g/mol, often symbolized by H4Y] is an excellent chelating agent. It forms very strong 1:1 complexes with almost every divalent and trivalent metal ion depending on solution conditions. Ignoring charges for the moment,

                EDTA + M   → MEDTA

 I think the following below links may help you in your analysis:

http://www.chem.uky.edu/courses/che226/Labs/030-Zn_EDTA.pdf

http://www.chem.uky.edu/courses/che226/labs/complexometric_zinc.html

Thanks

Dear Colleague,

I hope this message finds you well. Titrating Zinc Oxide (ZnO) in Calamine Lotion using complexometric titration involves several steps to accurately determine the zinc content. Below is a detailed and logical protocol for this process:

Materials and Reagents

Protocol

Example Calculation

Assume you titrated 1.00 g of Calamine Lotion with 0.01 M EDTA solution and used 25.0 mL (0.025 L) of EDTA to reach the endpoint.

Concentration of ZnO=(0.025×0.01×81.381.00)=0.02034 g/mL\text{Concentration of ZnO} = \left( \frac{0.025 \times 0.01 \times 81.38}{1.00} \right) = 0.02034 \text{ g/mL}Concentration of ZnO=(1.000.025×0.01×81.38​)=0.02034 g/mL

This result indicates that the concentration of ZnO in the Calamine Lotion is 0.02034 g/mL.

Notes and Tips

• Indicator Choice: While Eriochrome Black T is commonly used, other indicators like Murexide can also be used depending on the specific requirements and availability.
• Accurate pH: Maintaining the correct pH is critical for the stability of the Zn-EDTA complex. Always verify the pH before starting the titration.
• Sample Preparation: Ensure the sample is completely dissolved and free of particulates to avoid inaccuracies in the titration.

By following this protocol, you can accurately titrate ZnO in Calamine Lotion using complexometric titration.

Reviewing the protocols listed here may offer further guidance in addressing this issue