Experiment 35 Extraction of Iodine with Heptane

Important note Do not use an analytical balance to weigh iodine because its vapors are corrosive. Be cautious with iodine crystals, being careful not to spill any crystals on the floor or bench top. Wear gloves. 

Prepare 100.0 mL of a 0.0075 M solution of iodine (I2) in heptane solvent. Use this solution for the stock solution in step 4. 

Your instructor may elect to perform this step for you ahead of time. Prepare 25.0 mL of a water solution of iodine that also has potassium iodide added. The potassium iodide is added to increase the solubility so that the iodine dissolves completely in the water. This solution should be 0.025 M in iodine and 0.15 M in KI. 

From this solution, prepare 25.0 mL of a 0.00025 M solution of iodine in water. Pour this entire solution into a 125-mL separatory funnel. Stopper the funnel. 

Prepare a series of standard solutions of iodine in heptane, 25.0 mL each, by diluting the stock solution from step 1. The concentrations should be 0.00015, 0.00030, 0.00045, 0.00060, and 0.00075 M. 

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