User talk:Idoarev

NOTE: IF YOU HEAT A SUBSTANCE UNDER THE HOOD, KEEP IT THERE UNTIL IT COOLS. At the end of this lab be sure to include a chart in your laboratory notebook which summarizes the chemical tests, the substances tested and the color changes/results. A. REDUCTION OF THE CUPRIC ION: To 5ml of Benedict’s solution in each of three test tubes, add 3 drops of acetaldehyde to one test tube and 3 drops of acetone to another. The third test tube of Benedict’s solution serves as a blank (reference). Place all test tubes in a boiling water bath for at least 15 minutes. EXAMINE CAREFULLY and record results. How does Benedict’s solution differentiate between an aldehyde and ketone? 2Cu2+ + R-CHO 5OH-R-COO- + Cu2O + 3H2O B. SCHIFF’S REAGENT: Add 1ml of Schiff’s Reagent (p-rosaniline hydrochloride) to each of three test tubes. Add 3 drops each of acetaldehyde to one test tube of Schiff’s Reagent, benzaldehyde to another and acetone to the third. Shake and place in a beaker of cold water. Record color both before and after the reaction. NH2+ Cl- H2N NH2 p-rosaniline hydrochloride C. REDUCTION OF THE SILVER ION: Tollen’s Reagent [Ag(NH3)2+ ] is prepared by dropwise adding one drop of NaOH to 2ml of 10% AgNO3 in a CLEAN test tube. Add dilute NH4OH until the precipitate just dissolves. Add a few drops of acetaldehyde and warm gently. Record results. Clean the test tube with HNO3. Include the reaction in your notebook. R-CHO + Ag(NH3)2+ R-COO- + Ag (silver mirror)

OXIDATION OF ALCOHOL BY COPPER: Place about 1ml of ethanol in a test tube. Plunge a red hot copper spiral into it. Repeat 5 or 6 times. Note the odor cautiously. Add 2ml of water and 1 drop of 0.5% resorcinol solution. Stratify with 5ml of conc. H2SO4 as in “E”. Record results. Repeat with methanol. What functional group have you turned these alcohols into? G. OXIME FORMATION: To 2 grams of hydroxylamine hydrochloride dissolved in 4ml of water add 4ml of 30% NaOH solution. Cool in ice water and add 3.5ml of acetone, slowly and with vigorous shaking. Allow reaction to stand overnight so that crystals form. Dry crystals of acetoxime and compare the melting point with that in the literature. Of what practical purpose is oxime formation? Include the reaction in your notebook.