Chemistry – Atoms, elements and compounds - Elements, compounds and mixtures | e-Consult
Atoms, elements and compounds - Elements, compounds and mixtures (1 questions)
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To separate a mixture of iodine (I2) and potassium iodide (KI), the student can use a technique called solvent extraction. This involves dissolving the mixture in a suitable solvent and then using selective solubility to separate the components.
Procedure:
- Dissolve the mixture in hot water. Iodine is slightly soluble in hot water, while potassium iodide is very soluble.
- Allow the hot water to cool. As the water cools, the solubility of iodine decreases.
- The iodine will crystallize out of the solution as the water cools, forming purple crystals.
- The potassium iodide will remain dissolved in the water.
- The iodine crystals can be separated from the solution by filtration.
- The iodine crystals can then be further purified by recrystallization from hot water.
Principle: The separation is based on the principle of difference in solubility. Iodine has a lower solubility in cold water than potassium iodide. When the hot solution cools, the solubility of iodine decreases significantly, causing it to precipitate out of the solution as solid crystals. Potassium iodide remains dissolved in the water because it is highly soluble. This difference in solubility allows for the physical separation of the two components of the mixture.