• 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...

Introduction

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.

Middle

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.

Conclusion

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)

    In each oxidation, the dichromate is reduced to Cr3+ (green). No reaction occurs with a tertiary alcohol. SAFETY: Follow general safety procedures. Potassium dichromate is toxic also sulphuric acid is extremely corrosive so make reference to the relevant hazcards. Results Test 1 Test 2 Test 3 Test 4 Test 5

  2. To identify an organic unknown using basic cohesive chemical tests to discover the functional ...

    Phenol acts as a very weak acid which will neutralise a strong base. By adding sodium hydroxide to the Phenol Sodium Phenoxide is made along with water. Then if concentrated HCl is added a milky emulsion is formed indicating the presence of Phenol.

  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. Identification of an Organic Unknown.

    Hydrolysis and then testing for a carboxylic acid can test for the presence of an ester because esters hydrolyse to form carboxylic acids. Phenols are compounds containing a hydroxyl group attached to an aromatic ring, for example 2-methylphenol. Phenol produces a purple complex when mixed with iron (III)

  1. Identify an unknown organic compound.

    The use of measuring cylinders will enable accurate readings and again give accurate results. Throughout the experiment, the type of unknown will obviously need to be kept the same. The amounts of the unknown will need to be varied according to the chemicals it will be mixed with in the various tests.

  2. identifying an unknown compound

    Outcome - A change from clear to a silver precipitate on the side of the test tube indicates the presence of an aldehyde. If there is no change indicates a ketone. Explanation - Aldehydes are easily oxidised to acids. Ketone cannot be oxidised as there is no place for the oxygen from the oxidisation agent.

  1. 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.

  2. Titration with a primary standard.

    A black line on a white piece of paper held behind the buret will darken the meniscus and make it a little easier to read the volume. I would read this volume as 3.42 mL, do you agree with that? Diagram 9 To pipet 25.00 ml (note the significant figures)

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