• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11

Identification of an organic unknown

Extracts from this document...

Introduction

Identification of an organic unknown Introduction In this chemistry coursework, I am supplied with an unknown organic compound containing one of the following functional group: * Alkene * Primary alcohol * Tertiary alcohol * Aldehyde * Ketone * Carboxylic Acid * Ester * Phenol I am going to outline a sequence of simple chemical test that I could use to identify each group. Each test must be dependant on the result of previous test. I am going to write up a plan include a flow chat, and a procedure which provides fully details of each test with the expected observations and any necessary safety precaution. Also I will need to consider the equipment and apparatus and chemicals use. Primary and Tertiary alcohol Oxidation can be used to decide whether it a primary or tertiary alcohol. Oxidation with acidified potassium dichromate(VI) solution results in a colour change from orange to green due to the formation of Cr3+ ions, as long as there is not an excess of dichromate present. A colour change will therefore only occur with primary and secondary alcohol. The Lucas test is another way of distinguishing between primary and tertiary alcohols. It depends on substitution of chlorine for the hydroxyl group. The alcohol is shaken hard in a stoppered flask with concentrated hydrochloric acid and anhydrous zinc chloride. The flask is then allowed to stand. ...read more.

Middle

very flammable; therefore I must keep the stopper on the bottle as much as possible, keep the bottle away from flames and wear safety spectacles Tollens' reagent becomes explosive on evaporation. Therefore wash away residues immediately after use. Procedure 1. Put about 1cm3 of 0.05M AgNO3 into a very clean test tube and add three or four 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 all the little black specks of silver oxide). 3. Add one or two drops of unknown, shake the tube gently and place in a beaker of warm water. 4. Note observations and immediately rinse out the test tube. Positive results If a shinny silver mirror form, aldehydes presents. Negative results Ketones have no reaction with Tollens test. Fehling's test Fehling's test are similare to Tollens' test, except that copper(II) is used instead of silver(I) as the oxidizing agent. Fehling's regent must be freshly prepared before each used. Fehling's solution A is awueous copper(II) sulphate; Fehling's solution B contains alkali and tartrate ions. Equal volumes of Fehling's A and B should be mixed to give a deep blue solution of copper(II) tartrate complex. Equations Apparatus Safety spectacles Protective gloves Fehling's solution A and B Test tubes Hazards The unknown compound could be is very flammable; therefore I must keep the stopper on the bottle as much as possible, keep the bottle away from flames and wear safety spectacles Fehling's solution is corrosive, Safety spectacles and gloves must wear Procedure 1. ...read more.

Conclusion

Test tubes Hazard Warning Both phenol and bromine water attack the skin and give off irritating vapours. Therefore, safty spectacles and gloves must wear, avoid contact with skin, and keep stoppers on bottles as much as possible. Procedure 1. Into a test tube pour about 5 cm3 of water and add a spatula-measure of unknown. 2. Cork and shake until the phenol has dissolved. 3. Pour half the solution into another test tube for the reaction with neutral Iron(III) chloride solution. 4. Add about six drops of bromine water to the aqueous phenol. Shaking the test tube after the addition of each drop. 5. Note your observation. Positive results White precipitate and brown colour disappeared means phenol presents. Reaction with neutral Iron(III) chloride solution I could use this reaction as a confirmation test to distinguish phenols. Phenols produce a colour complex with this reagent. Apparatus Safety spectacles Protective gloves Iron(III) chloride solution, 0.5M FeCl3 Test tubes Hazard Warning Both phenol and bromine water attack the skin and give off irritating vapours. Therefore, safty spectacles and gloves must wear, avoid contact with skin, and keep stoppers on bottles as much as possible. Procedure 1. Into a test tube, pour about 1 cm3 of Iron(III) chloride solution. Add sodium carbonate solution, drop by drop, until a trace of the brown precipitate just remains after shaking 2. Add a few drops of neutral Iron(III) chloride solution to the solution prepared in the reaction with bromine water. 3. Note observation. Positive results Violet coloration means phenol presents. ?? ?? ?? ?? Sophie Lam ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Aqueous Chemistry essays

  1. Peer reviewed

    Identification of an Organic Unknown.

    4 star(s)

    I can back this conclusion up using the set of spectra provided for this substance. The Mass Spectrum shows that the compound has a mass of 72 - 73. The Infra Red spectrum shows that the compound has an aromatic C-H bond and a C=O bond (both of which are found in Ketones).

  2. How much Iron (II) in 100 grams of Spinach Oleracea?

    Wash the beaker and glass rod twice using a small volume of Sulphuric Acid (aq) to collect up any remaining Iron (II). 8) Wash the residue in the funnel once with a little Sulphuric Acid (aq) and collect the filtrate.

  1. Identification of an unknown organic compound

    shape (Revise A2 chemistry for OCR A by Helen Eccles and Mike Wooster) Aldehydes can be oxidized by reflux to carboxylic acids or be reduced to primary alcohols. The tests which I can use to identify an aldehyde are: * Tollens reagent - to about 4cm3 of silver nitrate solution

  2. identifying an unknown compound

    A water bath is used because some chemicals are potentially flammable. An orange to green colour change would indicate the alcohol. This colour change is due to dichromate being reduced from Cr2O72- (orange) to (green) Cr3+ . As this is the only alcohol we can assume this is the primary alcohol.

  1. Identification of an Organic Unknown.

    1.Add a solution of 2,4 dinitrophenylhydrazine +ve No precipitate Orange precipitate Formed 2.Add Fehlings reagent (blue) 3.Add Sodium Hydrogen Carbonate CO2 -ve +ve No CO2 Liberated No Change Turns to Red/brown 4. Add FeCl3 -ve +ve Turns black/purple No colour Change 5.

  2. Lipid Identification and Chromatography

    to the cell through water and be kept from that water through the layer of fatty acid tails surrounding it, with the hydrophilic phosphate groups surrounding the fatty acids. Chromatography Chromatography is a technique used to distinguish chemicals when they are in a mixture.

  1. I have been supplied with an unknown organic compound containing one of the following ...

    Condensation reaction occurs immediately followed by an elimination process. Add 5 drops of DNPH to 2cm of the unknown compound. Shake the test tube. A positive test is indicated by: An orange/red precipitate forms. 5) Test to distinguish between a ketone and an aldehyde Tollens' reagent Shows a positive test for aldehydes.

  2. Titration with a primary standard.

    Using a clean dry beaker, obtain about 70 ml of the unknown NaOH solution. 4. Transfer a small volume of the NaOH solution to the buret (already rinsed with water and distilled water) and rinse the buret wall with the solution.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work