Mrs. Amy Cook
February, 9 2011
Lab report on separation of mixtures
Purpose- The purpose of this lab is to separate or isolate the desired product from large amounts of solvent and by-products. It is also followed by a purification step that removes trace amounts of other substances from the final product. One of the experimental techniques that we used in the lab to separate or purify mixture is fractional crystallization. In the experiment we used fractional crystallization to resolve a mixture of salicylic acid and CUSO₄ .5H₂O in to its components. Since solubility is most important in this experiment, CUSO₄ is more soluble in the highly polar solvent H₂O than in a solvent of low polarity, such as ethanol. Procedure- 1. Obtain an unknown mixture and record its number 2, add 2.5g of the unknown mixture to a previously weighed, clean and dry 100ML beaker 3. Weigh the beaker containing the mixture and calculate the mass of the unknown 4. Add 50ML of water containing about 1ML OF 3M H₂SO₄ solution to the beaker 5. Heat the mixture on a hot plate, constantly stirring until all the solid material has dissolved 6. Avoid boiling the solution while heating it 7. Remove the beaker from the heat, cover it with a watch glass, and allow it to cool enough to be comfortable to the touch. 8. Place the beaker in an ice bath and after a little while you will see a large quantity of salicylic acid needles settled in the bottom of the beaker. 9. Keep the beaker in the ice bath until crystallization is complete. 10. set up a vacuum filtration apparatus and place a piece of filtration paper in the Buchner funnel 11. Swirl the beaker and pour its contents in to the Buchner funnel 12. Transfer the salicylic acid crystals as completely as possible to filter paper 13. Pour the...