• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

I have been supplied with an unknown organic compound containing one of the following functional groups: Alkene Primary alcohol Tertiary

Extracts from this document...


Assessed practical (skills P and A) Introduction I have been supplied with an unknown organic compound containing one of the following functional groups: * Alkene * Primary alcohol * Tertiary alcohol * Aldehyde * Ketone * Carboxylic acid * Ester * Phenol The organic compounds above all have different functional groups, and will react differently. Therefore in order to identify the functional group that the unknown compound contains I will carry out a series of experiments. I had to choose carefully which tests to use because each test should be dependant on the result of the previous test. Method 1) Test for the presence of an alkene: Bromine test Add 5 drops of bromine solution (a brown/orange colour) to 2cm of the unknown compound. Indication of a positive test The orange/brown solution decolourises. 2) Test for the presence of a primary alcohol: Heat the unknown organic compound gently (reflux) with potassium dichromate (VI), which is an oxidising agent, and concentrated H SO in distilling apparatus. Indication of a positive test The orange solution turns green, as the orange dichromate (VI) ...read more.


Drop by drop add ammonia solution until the precipitate of silver oxide dissolves. Add one or two drops of the unknown compound, shake the tube gently and place in a beaker of warm water. A positive test is indicated by: A silver mirror is produced on the sides of the test tube from the colourless solution. 6) Test for an alcohol (-OH) group Add three drops of the compound to be tested to 10drops of an acidified cerric ammonium nitrate solution (a yellow solution) The alcohol complexes with the cerric nitrate ion A positive test is indicated by: The immediate formation of red or red-brown colour indicates a positive test. If the unknown compound is not soluble in water, two layers will be present. A red colour in either layer will indicate a positive test. 7) Test for the presence of a carboxylic acid: Sodium bicarbonate test An acid/base reaction occurs. Sodium bicarbonate reacts with the carboxylic acid to give off carbon dioxide gas. Add a few drops of the unknown compound to 1cm of methanol and slowly add to 1cm of a saturated solution of sodium bicarbonate. ...read more.


Add 5 drops of FeCl solution (a yellow solution) to a test tube containing 2 drops of the unknown compound. A positive test is indicated by: The solution changes colour to a purple. . Risk Assessment * Phenolphthalein can cause skin contamination, always wear rubber gloves when handling. * Sodium Hydroxide is corrosive and an irritant. Handle carefully by wearing gloves and goggles * Potassium dichromate (VI) is toxic if inhaled, handle carefully and do not leave bottles uncapped. * Iron (III) chloride is irritating to eyes and skin so wear gloves and protective goggles. * 2,4 DNPH is toxic by skin contact. * Organic substances are flammable so all heating should be carried out in a water bath. * Clean up all chemical spills immediately, and dispose of all waste as directed. Apparatus * 10cm measuring cylinder * Teat pipette * Test tube rack * Water bath * Small beaker * Distilled water * Large beakers Reagents * 2,4-dinitrophenylhydrazine (DNPH) (aq) * 20 drops of 2M ammonia solution * 20 drops of 2M sodium hydroxide solution * Limewater * 5 drops Iron Chloride (5% FeCl ) * 5 drops Phenolphthalein indicator * 5 drops Bromine solution * Potassium dichromate (VI) (aq) * Concentrated sulphuric acid (aq) * 1cm 0. ...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)

    No colour change shows an ester. EXPLANATION: Primary alcohols are oxidised by acidified dichromate to aldehydes and then to acids. C2H5OH + [O] --> CH3CHO + H2O [O] is the oxygen from the oxidising agent then CH3CHO + [O] --> CH3COOH If this is done with a secondary alcohol, only a ketone forms.

  2. Identification of an Organic Unknown.

    Add bromine water -ve +ve No turns colourless change 6. Add potassium dichromate -ve +ve no change Turns green 7.Add sodium Effervescence 8. To confirm presence of ester, it should be Hydrolysed and tested for carboxylic acid. If positive then it is an ester.

  1. Electronic spectroscopy - Homoleptic chromium(III) complexes and the spectrochemical series.

    1.25g of the purple crystal was obtained. Given that the RMM of CrCl3�6H2O = 266.4g mol-1 and the RMM of [Cr(acac)3] = 349.2g mol-1, 1.30g/266.4g mol-1 = 4.88x10-3mol, so 1.70g of product is expected and this represents a percentage yield of 74%. The complex [Cr(NH3)6]Cl3 was prepared as follows.

  2. identifying an unknown compound

    When the silver nitrate with ammonia to form Tollen's reagent then the complex ion is formed [Ag (NH3) 2) +.This is reduced to silver during the process. Tollen, s reagent is the oxidising agent. Equipment and reagent: * Test tube * Pipette * Silver nitrate solution * Sodium hydroxide solution * Ammonia solution * Water bath 5.

  1. Titration with a primary standard.

    of sodium carbonate, you will use a 25 ml TD pipet and a rubber bulb. If the pipet does not fill above the mark, remove the rubber bulb squeeze it and reattach to continuing the sucking up of the liquid.

  2. Organic compound identification.

    Add a few drops of acidified potassium manganate (VII). From the results of these tests identify the TWO functional groups present in B and draw a possible structural formula. Predict the structures of the products formed when B reacts separately with (a) ethanol + concentrated H2SO4 (b) bromine liquid.

  1. Identification of an unknown organic compound

    The test I will be using to identify an alkene will be the bromine test. I will add 5 drops of bromine water then add 2 drops of the unknown organic compound and shake. If the bromine water is decolourised this means there is an alkene present.

  2. Quantitative Tests For Identifying Organic Functional Groups.

    H+ H - C-O-CH2CH3 + H2O O ?? H - C-OH + HO-CH2CH3 Aim: To identify 6 organic unknowns (Aldehyde, ketone, ester, alcohol, carboxylic acid, phenol). General apparatus: * 2,4-dinitrophenylhyrazine. * Methanol. * Pipette * Test tubes * Silver nitrate solution.

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