I did three mixed melting point trials that resulted in a melting point of 1200C to 1220C. The melting point range is small, which indicates a relatively pure substance. I did a mixed melting point trial to find out what substance I had. I used Benzoic Acid and Succinimide because they were the two substances in my melting point range. Just by comparing the characteristics of the two substances to my unknown, I assumed it to be Benzoic Acid. My unknown and Benzoic Acid had a fine, powdery texture to it, while Succinimide looked like crystals. The two mixed melting point range trials confirmed this.
Unknown number 18 is Benzoic Acid. A possible alternative would be Succinimide, because of the close melting points. Another possible alternative is Fluorene, which melts at slightly lower temperatures than my unknown does. Benzoic Acid is C7H602. Its structure is: My ppercent recovery was 28. 26%. During the dissolving of my unknown, there was still undissolved solid. This could have led toa smaller ppercent recovery. If you are not given the solubility data for your compound, then you must test for the solvent required. This is done by mixing the possible solvent and your solid together and gitating it, heating it, then cooling it.
It crystals form, you have your solvent. You dissolve your solid by using a hot solvent, and then cool it down to form crystals. The solution is heated so the solid can dissolve and the filtrate is cooled to lower the solubility, which causes the crystals to form.