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Identification of an organic unknown.

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Introduction

Identification of an organic unknown (Skill P) Introduction I am supplied with an unknown organic compound containing one of the following functional groups: * Alcohol * Aldehyde * Ketone * Carboxylic Acid * Ester * Phenol Organic compounds have different functional groups and therefore differ from each other. They also react differently, I will use this method to determine the type of organic compound I have. I will conduct various experiments to narrow down the choices. After gathering the relevant information I will produce a flow chart. Plan There are many different chemical tests, which enable us to identify an unknown compound. The only thing known about the compound is that it contains one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid, phenol or ester. I devised a sequence of tests that would identify which of the groups the sample contains. Initially I worked out what tests there are for each functional group, and decided which one to use on the basis that each test should be dependent on the result of the previous test, which helped me to arrange the sequence. Method Test for presence of alcohol: The Cerric Nitrate Test Reactions: The alcohol complexes with the cerric nitrate ion How to ...read more.

Middle

Tollen's reagent will cause silver atoms to coat the test tube in the presence of an aldehyde: a. This is a mixture of ammonia and silver nitrate, containing [Ag (NH3)] 2+ complex ions. b. Silver (I) ions are reduced are reduced to Ag when the aldehyde is oxidised. How to perform the test: Preparing the Tollens' reagent: 1. Put about 1 cm3 of 0.05 M AgNO3 into a very clean test tube and add 3-4 drops of sodium hydroxide solution. 2. Drop-by-drop, add ammonia solution until the precipitate of silver oxide nearly dissolves (do not try to get rid of the little black specs of silver oxide). 3. Add 1 or 2 drops of the unknown compound, shake the tube gently and place in a beaker of warm water. Note your observations and immediately rinse out the tube. A positive test is indicated by: A silver mirror is produced on the sides of the test tube from the colourless solution. 'Before' and 'after' situation for the oxidation of an aldehyde, in this case, ethanal. Test for presence of carboxylic acid: The Sodium Bicarbonate test Reactions An acid / base reaction occurs. ...read more.

Conclusion

* Eye protection must be worn at all times in the lab. (Wearing contact lenses is strongly discouraged.) * Memorize the location of all exits, showers, eye washes, fire extinguishers, and fire blankets. * Be certain that there are no flammables in the area when lighting a flame. * Be alert for hazards in the lab. Do not proceed with any experiment until you understand the hazards involved. * Report all injuries to your instructor, even if they appear to be minor. * Do not come into contact with any of the solvents or reagents used in this lab other than soap and water. Remove gloves and wash hands before leaving lab. * Clean up all chemical spills immediately, this includes drips on bottles. * Do not leave any bottle uncapped. * Dispose of all wastes as directed. (Ask before you dump.) Clean Up: 1. Discard wastes as described in the directions for each test. 2. DO NOT WASH or rinse the unknown vials with anything! Replace the caps to their proper vials, and return the unwashed unknown vials to your instructor. 3. Clean your test tubes, using a wire brush to remove any precipitates. 4. Return all standard samples and test reagents to their original sources. 5. Wipe down your work area of the lab bench with a damp sponge. ...read more.

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