How to Obtain Pure Iodine from a Mixture of Iodine and Lead Sulfate

Introduction

When dealing with the separation of iodine and lead sulfate, several methods can be employed to achieve the desired purity of iodine. This article will explore three different techniques: solvent extraction using chloroform, sublimation, and using hexanes as a solvent. Each method has its own merits and is suitable under different conditions.

1. Solvent Extraction

The first approach involves the use of a solvent that can effectively separate iodine from lead sulfate. Common solvents that iodine can dissolve in include chloroform (CCl4), tetrachloro methane, and hexane. Here are the detailed steps:

Materials Needed:

Separation funnel Chloroform (CCl4) or tetrachloro methane Hexane

Procedure:

Add the mixture of iodine and lead sulfate to a separation funnel. Slowly add the chosen solvent to the funnel, ensuring that the iodine dissolves in it while the lead sulfate does not. Shake the separation funnel vigorously to ensure thorough mixing. Open the funnel at the top and gently rotate it upside down to allow any vapors to escape. Let the solution stand for some time to allow the layers to separate. The iodine will be present in the solvent fraction, which can be collected by draining it off.

2. Sublimation Technique

Another effective method is sublimation, which involves changing a substance directly from a solid to a gas without going through a liquid phase. This can be particularly useful if you need a very pure form of iodine.

Procedure:

Place the mixture in a vacuum desiccator or a similar setup that allows gentle warming. Heat the mixture gently to sublime the iodine vapor away from the mixture. Cool the vapor in a cold trap or a chilled surface to deposit the solid iodine.

3. Hexanes as a Solvent

A third method involves dissolving the iodine in hexanes, a solvent that is insoluble in lead sulfate. Here are the steps:

Materials Needed:

Pure hexanes Potassium sulfate (K2SO4) or another drying agent to remove any moisture

Procedure:

Add a sufficient amount of hexanes to the mixture. Mix until the iodine is fully dissolved. Filter the mixture to remove lead sulfate. Evaporate the hexanes using a rotary evaporator or by suction filtration. Collect the remaining solid iodine.

Conclusion

Both techniques offer effective ways to obtain pure iodine from a mixture of iodine and lead sulfate. The choice of method depends on the availability of materials and specific requirements. Solvent extraction is straightforward and uses common lab equipment, sublimation allows for highly pure iodine production, while using hexanes is simple and can be done with readily available chemicals.