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

Identification of an unkown compound

Extracts from this document...

Introduction

Identification of an Organic Unknown (Skill P) Equipment: Test tubes Pipette Water Bath Sodium Bicarbonate Methanol Bromine Water 2, 4 DNPH Ethanol Silver Nitrate solution Sodium Hydroxide solution Ammonia solution Potassium Dichromate solution Sulphuric acid General safety: * In the event of getting a substance in my eye I will wash it out with cold water immediately. Safety goggles will be worn for all of the experiments. * If irritation is felt on my skin due to having contact with a substance I will wash the area of skin immediately with cold water. * If a spillage of any of the substances used occurs, I will notify those around me straight away. If the substance is not considered harmful I will clear it up personally, if it is hazardous I will inform a technician. * In the event of swallowing a harmful substance, medical help would be received be urgently requested. * Highly flammable substances must be kept at least 1 metre away form an open flame. * When tidying up at the end of my experiments it will be important to check those solutions that are safe to pour down the sinks and those that need to be handled with more care. 1) Test for an Alkene or Phenol The reaction of an alkene with Bromine water is an electrophilic addition reaction; the alkene will open up its double bond and form bonds between its carbon atoms and the electrophilic Bromine atoms. ...read more.

Middle

Once this is achieved add 2cm3 of 2,4 DNPH, using a pipette, to the solution and agitate for 1 minute, before leaving to stand for 5 minutes in a water bath . Result: The formation of a bright orange precipitate indicates the presence of a carbonyl compound, which will be an Aldehyde or a Ketone. If no change occurs then an unknown functional group still remains. Hazards: 2, 4 DNPH is explosive and toxic, so must be handled in a fume cupboard whilst wearing gloves. Also I am aware that ethanol is highly flammable, so it will be kept away from any open flames. 4) Test for an Aldehyde Aldehydes are easily oxidised to acids, whereas Ketones cannot be oxidised, as there is no place for the oxygen from the oxidising agent to attach on to. When the silver nitrate is mixed with ammonia to form Tollen's reagent, the complex ion [Ag (NH3) 2]+ is formed. [Ag (NH3) 2]+ + e- Ag (s) + 3NH2 This is reduced to silver during the process of oxidation. Tollen's reagent is the oxidising agent. Into a test tube, place 2cm3 of Silver nitrate solution and add 1 drop of dilute Sodium Hydroxide (NaOH). Add ammonia solution drop wise until the initially formed brown precipitate of silver oxide is re-dissolved. Then add 5 drops of Methanol to the solution and 5 drops of the unknown compound. ...read more.

Conclusion

Likewise, goggle must be worn as getting the reagent in your eye can be dangerous. 7) Test for a Carboxylic acid Using a Pipette add approximately 6 drops of the unknown compound solution and mix with 3 drops of methanol, to this then add 2 crystals of NaHCO3 and shake the test tube vigorously. Result: Solubility will be indicated by a colour change, or the evolution of Carbon dioxide. In this case a Carboxylic acid is present. To test for the evolution of Carbon dioxide, and thus the presence of a Carboxylic acid, the limewater test can be used. Lime water is a solution of calcium hydroxide (slaked lime). If Carbon dioxide is bubbled through it, a solid precipitate of Calcium Carbonate is formed. Calcium Carbonate is chalk or limestone, it is this that makes the lime water cloudy. calcium hydroxide + carbon dioxide calcium carbonate + water. Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l) Equipment: Bunsen burner Bung Rubber tube Hazards: Sodium Hydrogen Carbonate may cause skin irritation if constantly exposed to it, so gloves should be used. It is also Moisture sensitive so should be kept in a closed container, before and during the experiment. As mentioned earlier I am aware as to the dangers of Methanol. If all the tests prove a negative result then the unknown organic compound should be an Ester. All experiments should be carried out at least 3 times to be completely certain however. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Organic 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 AS and A Level Organic Chemistry essays

  1. Marked by a teacher

    Reactions of aldehydes and ketones. The purpose of this experiment is to compare ...

    5 star(s)

    Cr2O72- Cr3+ Besides acidified dichromate solution, acidified potassium permanganate solution can also be used as an oxidizing agent. The equation of its reduction is: MnO4- + 8H+ +5e- Mn2+ + 4H2O However, this oxidation test cannot be used to confirm that the sample is a aldehyde as there are also

  2. Identification of an Unknown Organic Compound

    Then add 2.5cm3 of this solution to the acidified potassium dichromate solution as mention earlier. Then gently warm the test tube containing the solution in a water bath for 5 minutes. If there is a colour change of the solution from orange to green, then it's positive for a Primary or Secondary Alcohol.

  1. Find the enthalpy change of combustion of a number of alcohol's' so that you ...

    To improve this I should use a more accurate weighing instrument to measure the alcohol in the spirit burner before and after the experiment. This would have meant that a more accurate enthalpy change of combustion value to be worked out.

  2. The aim of this experiment is to produce Aspirin. This is an estrification in ...

    Preparing the burette The burette was filled with distilled water; checks were made so that there were no leaks. Using a small funnel, 5-10cm3 of the prepared solution was added to the burette. The funnel was then removed. The burette was then taken from the stand and tipped and rotated to wash the inside surface with the solution.

  1. The aim of this experiment is to investigate the enthalpy change of combustion for ...

    From extrapolating the line of best fit I deduced a value of -1360KJ/mol this is more likely to be the value recorded had I had time to do repeat readings for the alcohols. A line of best fit is hard to draw on graph one as the results are less accurate and I am unsure which are the anomalous results.

  2. Is Benzene an Alkene?

    The location of the C-C and C=C bonds also alternate. If benzene was to be labelled as an alkene, then surely it would follow the same pattern. This is not the case however. X-ray crystal structures have revealed that the bonds within benzene do not actually alternate in length, allowing benzene to have its hexagonal, planar structure.

  1. investigating the amount of ascorbic acid present in fruit

    dip is on the line, whilst using a white tile to accurately measure 90.00cm3 of distilled water. 4. Mix the 90.00cm3 distilled water with the 10.00g of solid acetic acid to make the solution. 5. Use distilled water to clear out any bits of the solid acetic acid that still maybe on the spatula and weighing boat.

  2. Identifying An Unknown Compound

    Follow this with approx. 5cm3 of distilled water and 2cm3 of sodium carbonate solution. Watch for effervescence. Safety: Sodium Carbonate solution is an irritant. Contact with skin and eyes should be avoided, should it occur, the affected area should be washed thoroughly under water.

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